Gameplay isnt the most important thing in games.

[Nuvendil]

I think that interaction, whatever form it takes, and a failure state, implied or actual, is the most important element. If that's how you want to define "gameplay," than I must disagree, it is most important because it is the very definition of what a game is. To remove all underlying principles that define the bounds of a medium is to do the medium a disservice. Recognizing those bounds, those principles, is what allows the medium to advance and provide that unique gratification that only that medium can provide. TV, Movies, traditional Art, Theater, Music, all these art forms provide unique gratification that the others cannot through use of unique aspects the others lack. They have progressed by recognizing that. In games it is the same. You can't just focus on "the feeling," but rather the unique gratification and more importantly, it's source. And I believe that interaction that promotes player investment is that unique aspect. If you lack that, then you sacrifice the most important aspect of a game and it becomes a less powerful representation of the medium. And the more you use that unique aspect, the more potentially potent that gratification comes.