I actually disagree with the "Gameplay must not serve story, but the other way around" sentiment. I don't mean that story can't serve a purpose of complementing the gameplay at ALL, but the thing is, I think gameplay can (and should more often) be used as a means to convey and complement the story. It's all right for gameplay to be the second banana, sometimes. Cutscenes go directly against this philosophy- the interactivity provided by gameplay being interrupted actively hurts any story (especially seeing as very, very few 3D games manage to not look horrible while doing it).
Let me elaborate.
So, story serving the gameplay would mean that story improves the gameplay, and that is the story's purpose, right? Well, I feel like that discards, disregards the merit of a game's story's merit as a story. I don't mean to imply that a game's story shouldn't improve its gameplay of course.
However, if the gameplay's main purpose is enhancing and complementing the story, I think we can have some utterly incredible stories -experiences- on our hands.
I think I'll be better off with examples from now on.
Case #1- Zero Escape. Everybody who has played these games knows that they can only be done in a game format, and loves them for the story. This game's gameplay? Room escape puzzles (which are NOT the reason the game is special, at ALL), and some choices you make here and there. It's the story that this series is loved for, and it's all thanks to particular gameplay elements that come into play late in the story.
Case #2- Persona. Persona's gameplay, besides standard turn-based JRPG fare with an addictive Persona fusion mechanic and bucketloads of style thrown in, is spending time with people around where you live, take part in jobs, improving your ingame character (Charm, Courage, etc.), making new friends. The "gameplay" part here is just walking up to people/places and initiating dialogue. Is it anything special? No. However, the way it's integrated into the story, its themes and character interactions make Persona something special and is the reason so many of us are so invested in the series. Hell, Persona 4's main story is far from being a masterpiece but the character interactions and the gameplay-story integration is so well done that a plot I would not have cared for otherwise has made me shed more tears than any other piece of media I have ever consumed.
Case #3- Soul Sacrifice (Delta). This one's a bit different from the others in that its story and gameplay aren't really separable since they feed into each other equally, but having to sacrifice a person you just defeated, or just someone you care about, with your own hands adds a peculiar and unexpectedly heavy weight on you, and the game has some incredible story moments based around the story. The prologue, for one, is a masterpiece.
Case #4- Tearaway. People say Tearaway has repetitive combat, overly simplistic platforming, and more style than substance. I can discredit none of these claims entirely, however, it doesn't mean that the gameplay complements the story- In fact, it creates a simply unique experience. Drawing crowns and snowflakes, and seeing them affect the level you are in. Seeing your own face in the sun, and being, as yourself, an integral part of the game's story and world. Tapping the rear pad to make iota bounce, or poking a finger into the world to toss Scraps around. The game takes a very, incredibly simplistic story, and by weaving you into it becomes a narrative masterpiece.
Playing games solely for the sake of the gameplay, while understandable, is missing out on both already existing masterpieces out there and diminishing the potential of video games as a storytelling medium.