I'm all for shedding triviality and creating shorter experiences. It seems that's all I have time for these days, anyway.

I've never liked the triviality in game design, either - while I tend to be very result-oriented in real life, I am very process-oriented in games and I tend to focus heavily on moment-to-moment feel and overriding purpose rather than points and achievements and such.
In the game I'm working on now, in fact, I'm still trying to defend my choice (to myself) to keep the game-ness simple and not to add things like achievements, points, upgrades and all that stuff that I find pointless but that I know will increase the ratings on Flash game portals...
What captures a notplayer - also captures a player, but through the fog of microgoal-feedback loops - is a world to wander, an atmosphere. In a way, this is an advantage the notgame has, as it ditches or reduces these loops, allowing space for other experiences and reactions to breathe and grow. We can wander. For me, this was what I liked best about The Path, not Grandma's house (the most plot-like element, I guess) but the forest itself, where the connections were neither fixed nor obvious, but the conjured world was dense and rich and intriguing. Which is a lot like travel, but unlike game travel, where it is all about both the destination, and the struggle (realised in short, short bursts), but the meandering and pseudo-aimlessness.
This is what I like too, but I don't know that this is all there is to notgames. It is certainly not all there is to games, since it's one of many gameplay types in several classification systems:
Easy Fun in Nicole Lazzaro's Four Fun Keys,
Explorer play in Richard Bartle's player suits,
Wanderer play in Chris Bateman's DGD1,and
Seeker play in Chris Bateman's more recent BrainHex model
Of course, it is my preferred play mode, generally speaking, but I wouldn't assume that that's all notgames can be. Certainly a fruitful starting point though.

And walking through a forest, yes. I have to say, playing The Path was an experience that came closest to that of walking through a real forest, more than any other game, though it was more like a hint of the experience than the actual thing. (So many of these games and things I admire are like hints rather than the real thing, really.) But I've had some thoughts about what that would have to look like, for me. Maybe I'll write more about it in another forum thread.