Maybe what's missing is that the developers who tend to want refinement are often mainstream-focused, as in wanting to do more traditional games?
Yeah, pretty is pretty much it. Football simulators, match-3, hidden-objects, and other more "gamey" (and mainstream) videogames have been doing this for a long time.
I just have gotten the feeling over the years that much of the more experimental game makers do not tend to stay with a specific game for too long. And yeah, I saw Chris Hecker's mini talk on this (which I think is the one you mentioned) and I agree. Braid is a good example, although I think it might have been possible to go even further with it (especially how the texts can relate to the actual gameplay and whatnot). It might have been more interesting if Blow made refined the 2D time-design instead of making a first person 3D project. Braid is perhaps not the best of examples since it is still very traditional it's approach (levels to complete, evident goals, all interaction are directly connected to completing goals, etc)
I understand there is a very fuzzy line here, but I the general gist is that when it comes to more nontraditional types of play for videogames, we have not explored the depth at all. Action games, puzzle games, etc have explored this for as long as video games have exited (around 40 years) and also build upon a foundation set in sports and traditional games (cards, boardgames, etc). Therefore I think that specializing is of extra importance, because there might be a lot that we are missing out on that cannot be grasps during the first attempts.