Art has always been important in games, pretty much since the beginning.
We see how people buy games that have the same mechanics and zero innovation just because they look much better than before.
But now we have the indie games movement, where awful-looking games like “Minecraft” have a tremendous success.
I would say that there is no reason to make a game that doesn’t look good, look at Dustforce!
old school game mechanics, with some new twists and adjustments and awesome graphics.
Dust: An Elysian Tail
Astonishing art, beautiful animation.
So… make retro games, use classic gameplay mechanics, but add the most beautiful, colorful HD art you can do!