Great discussion, people! Keep 'em coming. Oh, and just a little disclaimer. I'm in no way endorsing the thesis that story should be the sole or even prevalent aspect of an RPG. Far from that. I love battling, beating bosses, and doing sidequests as much as anyone else. But, in my personal case, the experience becomes much more richer and fuller if there's a strong narrative backing up all the gameplay aspects. It provides more of a reason to stick with the game to completion. If we don't give a single damn about the characters or the world they inhabit, why even help them trough their journey in the first place? There have been cases in which I stuck with a game because the gameplay aspect was entertaining enough. For example, I stuck with FFVIII until the end and even went as far as doing every sidequest (including beating Omega Weapon) because I love the classic Final Fantasy ATB system. However there are some things that I find unacceptable: 1) The only truly useful GF in combat was Doomtrain for his awesome ability to inflict enemies with a million status effects, and 2) even though early in the game GFs are useful to inflict damage they become obsolete pronto as you refine cards and equip them to buff up stats because contrary to popular legend base stats do matter in FFVIII to a certain extent. That's in the gameplay department as for story, as I progressed through it I thought "Wow, Squall spends more than half the game being an insolent twerp and now they want me to believe that he falls head over heels in love with Rinoa and is all heroic and selfless." At least with Cloud you had somewhat of an excuse, because he was subjected to a lot experiments. But, as much as I love Barret's backstory with Marlene, they did a great disservice to his character by making him curse every other word.
Every fantasy or sci-fi story requires suspension of disbelief, but that doesn't mean that the character's personalities don't need to be well defined and constructed.
In the end everything requires balance. I doubt anyone (including myself) would like to play a game where the battle system and character progression are so irremediably broken as to render the game nigh unplayable even if the story is absolutely genius. In similar fashion, I find it hard to believe anyone would waste 50-60 hours of their time in a game where they have absolutely no emotional investment in the narrative. It'd be akin to masochism.