Every medium brings with it its own unique potentials and challenges, but no one looks at a film and finds it impressive just because it isn't a photograph in the same way that no one looks at a building and finds it impressive just because it isn't a painting.
This is a rather good articulation of this argument, which in other discussions I've seen just derail everything into Essentialists VS Pluralists, or however you want to slice it.
I think there's actually a much more pragmatic argument for "games should do what games do well" which is just that we look like immature idiots every single time we try to copy other media (read: cinema).
Seriously, when people look back on the mainstream game industry a few decades from now, they're going to see a bunch of executives and creatives with their fingers in their ears saying "La la la, we can do 'blockbuster gravitas' just as well as Bruckheimer, even though our actors look like weird mannequins and our scripts suck and our fictions are usually so poorly thought out and brittle that players actively undermine the themes and story just by playing the game." Et cetera. It's just not worth playing that game (pun intended). Indies tend to understand this much better.
We should definitely strive to do scripts and characters better, and effort is equally well spent (and understand I'm arguing for all possible directions
here, no single right way to go) striking out into the massive swathes of terra incognita that we know are there. Chances are, when the public finally shows up at our door pointing to a group of games and saying "Holy crap, you guys went and made ART!" it'll be stuff from that territory. Some NYT guy seems to agree
Because face it, we can already ape other media semi-competently now and it's just digging us deeper into a cultural ghetto. Guess what? Movies are better movies than games. Most existing story-driven games are, when you peel everything away, just "television with a hand crank" (no non-trivial interactivity) or "one good story and 1000 ways to ruin it" (interactivity that ultimately undermines the expressive thrust of the piece).
Part of figuring out what storytelling means in games involves making enough of a clean break with cinema to be able to transcend your influences. All the really good game stories do this to some extent. I'm probably preaching to the choir at this point.
All of this will work out fine if the designers who are really interested in story and cinema go off and chase their idea of awesomeness, and the really ludo-minded people chase theirs, and so on and so forth. The way to "solve" this problem is diversity. Part of why some (annoying, uninformed) people write off comics is because for a long time they held themselves to a single type of subject matter and style of storytelling.