In the Original you had a total of 16 hearts and outside of random heart drops or the occasional fairy only up to two doses of potion to bring that back during a dungeon run.
Zelda 1 was the only one that was actually challenging in terms of combat, though, and placed a lot of emphasis on like, being able to navigate the rooms. Part of this was because you were more limited in terms of health, like you said, but also you just had a much smaller attack radius. I mean look you could attack in one direction. That was it. In the LttP-style games, your sword swing has a lot of reach and you get spin attacks, and the 3D Zeldas have z-targeting.
The things you mentioned about LttP, though, specifically get at why it bugged me so much.
1) Dark World enemies. Yeah, they do a lot more damage. But they aren't really behaving any more /interestingly/ than their light world equivalents. They just hurt a lot more when they get a hit in. Which really isn't that fun to me because in Zelda 1, the enemies behaved differently and took a degree of strategy to manage, whereas in LttP it gets overly reflexy in a game that doesn't really have controls that are conducive to that.
2) I thought that a lot of the optional overworld items were just outright obtuse to get.
3) There was kind of an issue I had with LttP that was addressed a lot in the GBC games but was weirdly absent in the rest of the series -- a lot of the items you found weren't that useful on the map itself, which sort of made exploration less fun. The overworlds in the GBC zeldas were like these big lovely dungeons in their own right.
Anyway, Wind Waker was odd in that, at least one one level, it was one of the most open Zeldas. AFTER the awkward stealth bit, you really can sale to a fucklot of places (whether you have the patience for this is arguable, mind). There's just not much to find though. A bunch of generic floating orc platforms with... nothing. There's not even an interesting collectible sidequest. I LIKED finding skulltulas and gold bugs in OoT in TP. WW had butterfly medallions that didn't seem to serve a purpose?
(I thought that Ultima 8 was actually rather good zelda-like game with rather good exploration but everyone hates Ultima 8 so whatever).
That too was another issue that had become an increasing problem throughout the series. Link's ever evolving moveset continuously altered the balance of a given game's challenge. In the original, outside of sword beams at full health all you had was a simple stab covering one title's length in front of you. Granted the difference between having sword beams and not having them was night and day but no game since has ever given you a true equivalent (the GB/C games comes closest but no game freely gives you sword beams out of the gate with no strings attached beyond the full health requirement with the same effectiveness that Zelda1's beams have).
I felt that ALttP made a fair compromise that was hindered only by questionable enemy disbursement. After all, it makes sense that you can slash with a sword and not just stab with it. At least sword beams in that game were so heavily nerfed that at times it was almost preferable to not have it on (like when you go in for a swipe with your sword but the beam registers the hit first which hits for probably significantly less damage by that point).
But to me, it was when Z-Targeting came around that the Zelda series lost a significant amount of challenge since once you locked on you were effectively in control of the fight unless something could bypass your shield (and little could). It's only been recently that the matter has been addressed with the shield's heavy nerfing (requires an active item slot and active use in the GB/C/A games, some attacks can temporarily break your guard in TP, and now with shield durability in addition to the other two SS).
Besides nothing was as ridiculous as WW's sense move that basically gave you a powerful defense bypassing counterattack with almost no guard or punish for it. Great spin was a bit too situational but that sense move made even the toughest enemies into minor speed bumps at best and I don't think anything before or since was as broken as that was.
As for your followup points, I thought that....
1) There were quite a few enemies that were difficult or impossible to deal with using just the sword alone. Of course almost all of these enemies could be dealt with by using other items that would typically one shot them (Dark Fairies, Gibdos, Chu-chus, Gelzaps, Red Cyclops, Goryias, those green penguin guys from level 5, ect...). Additionally most of the more interesting enemies were hiding out in dungeons (although Lionels could've existed for more than two screens).
2) Admittedly I liked and still like the idea of having important items kinda sitting off to the side ready to be obtained at your convenience rather than being handed an item or the means to get an item because now is the time for you to have that item and you can't go any further without it. And between the hints provided by NPCs and being prominent points of interest along your path, only the Magic Cape, the Cane of Bryna, and Bottle#3 were actually obtuse to locate.
3) Basically see #2. To a certain extent having portions of the map inaccessible to you from the start isn't the problem per say (hell even the original locked you out of some stuff in the beginning), but that having only a tiny piece open at the start with the other parts unlocked bit by bit can be really annoying if done poorly. LA is probably the only one that get away with this since there's enough unlocked early enough that reaching later dungeons simply means heading to one of the few remaining unexplored corners and filling it in (i.e. you can have most of the map explored by the time you enter level 5). Plus I find it annoying to have to crack open my inventory every other screen to put on some bracelets to lift a rock out of the way. (kinda like having to stop and either strap on or slip off some boots depending on whether you want to sink or swim).
i wonder if nintendo cares about some fans abandoning the series due to motion controls. it wasnt a big deal with TP since i had the choice of the gc version. do console makers have something to gain if they can get core gamers to accept motion controls?
Unique gameplay? You MIGHT be able to replicate this on a controller with clickable sticks (clicking being thrusting) and sacrificing camera control on the right stick, but this isn't like TP where it's literally mapping button functions to shaking a controller. Plus frankly this is A LOT more friendly to traditional types of gameplay than pure Kinect or touch screen controls, here you can reasonably mix it to varying degrees since usually aiming IS a lot better on a Wii Remote than an analog stick.
With that said Zelda's got bigger issues than how you control the game, it's been frequently argued that the Motion Plus additions are the ONLY really good thing Skyward Sword did gameplay-wise.
This post hits upon one of my biggest beefs with the current gaming community, the complete and utter fear and loathing of change. I feel that if we had gone with 20 years of Atari joysticks before somebody came along and introduced the D-pad people would be flipping their shit just like they are over any instance of waggle.
It takes time, experimentation, and refinements to find the best ways to integrate new methods of control and game design. Take 3D games, they weren't automatically good over night. It took many attempts and the better part of an entire console generation before a fluid and effective gameplay experience was finally achieved. Same with utilizing multiple screens for a single game as well as touch screen interfaces. Many have since seen the benefits of multiple screens segregating obtrusive UI from the gameplay field as well as providing instantaneous access to previously buried functions, and iOS games wouldn't even be possible if it weren't for touch screen interface compensating for a devoted control interface which doesn't play well with standard phone interfaces.
I feel that the potential is there and we're just now beginning to see it beyond FPS applications. As for SS and Zelda in general; I'm letting this pass as it's obvious that the greatest amount of effort went into making the game playable. It'll be the next mainline Zelda that makes or breaks my interest since it should, in theory, be focusing on refinement rather than innovation.