AAA games: 3D, built for high-resolution, high-detail, scaling ain't no thing.
Indie games: 2D, typically built for low-resolutions, most textures/sprites drawn at-resolution.
Let's face it, as much as we love them chunky pixels, you just can't scale 640x480 up to today's modern resolutions. It's like getting grandma's teeth shoved right up in your face. Big, blocky, two feet away from your eyes. Nobody wants that.
Yes... That explains it. AAA titles are 100% 3D nowadays, so scaling is irrelevant. On the other hand some indie games are pixel art and pixel art by its nature looks good only on perfect pixel screen, due to LCD technicals the perfect pixels can be achieved only in native resolution (sometimes I miss the old convenient CTR's) and native resolutions vary greatly, therefore the only reasonable option to make it look good is to use windowed mode...
Another observation, on BigFishGames there are mostly indie games and these AFAIR all start in fullscreen mode. So, I wonder, it is because:
a) they have no pixelart games and with 2D but non pixelart it is OK to scale
b) casual players (that portal is extremely casual) do not care about native resolution prettiness
c) historical reasons, the portal started in CTR era and they simply continue adding games in default fullscreen because it was always done that way and all other games there do it
Basicly, I'm trying to find an answer to a question if it is viable to use non native resolution (make it run always in 1024x768 with an option for a windowed mode) for 2D graphics that is not pixelart and if the answer differs depending on what my target audience is (casual vs hardcore).