Not that you ever *need* a light blade beyond Mythra. Really people just wanted KOS-MOS because she was a returning character. The fact that she is one of the ten or so strongest blades is just a bonus.
A similar statement could be made about half of the game's systems.
Pouch Items were both one of the few ways to cut cooldown times (so that you were faster throwing out Arts), and almost completely forgettable (the 'almost' stemmed from Blade Growth Trees' having the stuff as a fairly common unlocking requirement; once you guessed the correct item; as well as eventual Affinity farming for when you just didn't have enough time/game left to farm the stuff). Aux Cores were a second layer of Accessories/Gems &| Mods from XBC/X, but hideously cumbersome and only even worth using at Rank V due to a lack of sorting, limited capacity shenanigans and required material farming. And likewise, Accessories had a host of effects that were mostly academic because, until one of the later updates, characters were limited to only two, which often meant choosing between the Accessories that jacked up your Attack Power, or your Luck. And who here ever noticed or recalls how all Blades have Role modifiers that provide percentage based multipliers to certain stats when having that Blade active? And then there was Poppi's Tiger Tiger rigmarole (which most couldn't even be assed to bother with and effectively had a worthless party member until the NG+ Shops became a thing) or certain individual Blade sidequests like Vess's
Riceballs Hamburgers Dumplings, Pyra's Cooking or the hell that was that one Blade's Mercenary Dispatch sidequest (never pulled her, never had to deal with it).
And so on...
Because seriously, most of these fell away in usefulness anyways once Mythra unlocks her ability to instantly recharge Arts through Art Cancels and Rex can suddenly instantly charge up his Arts and Blade Combos and then flip the switch to his other stupidly overpowered Blade to detonate all the goddamn Orbs for massive Finishing Strikes (I love how, prior to the DLC, Rex was the only character to have a very specific multi-Blade combo between two of his plot Blades, unlocked after the above and is completely redundant beyond Rule of Cool).
But I mention all this not because I don't like XBC2, but because the Torna expansion fixes most of these issues and shows us what we could've gotten had BotW not cannibalized Monolithsoft's workforce during XBC2's development.