TC is right. Story and gameplay are undeniably interconnected. Many developers will tell you that as well. What people list as exceptions aren't really. People still excuse a lot of things in video games when it comes to story, ie. unrealistic dialogue sequences, poor subtext, character motivation that doesn't fit their behavior, and the list goes on, yet they're "amazing" stories to gamers.
Xenogears. Anyone who's played it knows what I'm talking about. The story is incredible, one of the best I've ever seen in any form of media. The gameplay... Eh. It felt outdated when it was released. It's the only game of its kind, at least among those I've played. However, it had several useless mechanics, grinding for deathblows was tedious (especially since they're all you use after you learn them), and ether attacks were useless until most of the way through the game. I think the encounter rate was too high as well.
http://www.youtube.com/ShadianVise TLoZ: Oracle of Ages playthrough in progress.
I can think of games that have "O.K." gameplay, but fun stories and characters. I would say that of the series I really love, Ryûga gotoku / Yakuza, even.
Games with *terrible* gameplay and reportedly good stories would be like ... Heavy Rain and L.A. Noire, tho' I personally think they're a little easy to figure out and once you know the cliché twists and such, they're just not really worth playing.
I think games that are almost purely story can definitely sell and be appreciated, but I think they are not going to fare well compared to games that focus on delivering more gameplay than story. The whole "debate" is silly to me as the actual theory behind the game and how they deliver it are obviously way more important than a story or presentation, but I would also say that if you do not have good designs, a compelling tale, or interesting characters, the game will probably just be ignored in this saturated market.
So, I mean, presentation is important, still, if you want to create an "A" title. However, it's just not as important as crafting a good system and challenging people to want to keep doing the basic things of the gameplay.
At the same time, I don't think games have to all be completely new approaches to gaming theory with completely unique ideas, or anything. Those are always nice when they show up but they don't usually go to far past that gimmick. Games just need to be crafted well.
Ryuuga Gotoku (Yakuza) series text FAQs available at GameFAQs PSN: hatoriki_kai, XBL: hatoriki, YouTube: ryled, Twitter: @Hatoriki, Me: Bored