In short, low-res is easy?but again I say, it isn't a stylistic choice.
Why the F can't it be a stylistic choice? And what are you implying by stating that? And no, it's not easy to make top quality lowres stuff. It's still true though what Quazi said and I like to think that you're getting at that when you label it "easy".
We are no longer in an era where sellable games can afford to have their art created by programmers instead of artists, because even Joe Shmuck can tell when the art is poorly made.
Naturally there is bad lowres art. As there is bad HD art. Poorly made graphics can't be defined by the resolution or graphical style only imho. So you're saying games shouldn't have poorly made graphics. Yeah, so what about well made retro art? It's automatically poor because it's lowres?
Look, for example, at Cave Story and Spelunky: both games are either available or "coming soon" to consoles, and both featured low-resolution art. Notice I say "featured": now that they've got some funding, both are getting a graphical overhaul. This isn't a coincidence. Low-resolution art is sellable only for nostalgia value: it isn't now, it isn't valuable.
Of course HD graphics do appeal more to the mass market. And after all those games are being made to sell copies. This doesn't mean games without HD aren't valuable. What's the value of the original Cave Story game? Doesn't it have any because it's free and lowres? It's still widely considered the best indie game ever. Unless value equals money for you, I'm not quite sure what you're trying to say.
Also if you give a statement that a 2d game should be HD because we're not in the 90s anymore and all... it's basically evidence of you not considering games to be art at all.
Don't get me wrong. By all means, make a HD game. I enjoy those too as I enjoy all well made games. But there's still one good reason why people should keep making retro games: because they want to.