Graphics matter, but it's like you said, not make or break. Last game I played was Hotline Miami 2, which looks very retro. Good game, but very frustrating for a spaz like me.
As far as frames per second, I always take 60fps when all things are equal. However, it'n not that big of a deal for me to play in 30 FPS. I'll give you an example. I loved Project Gotham Racing on the Xbox, which ran at 60fps. Played it quite a bit. Eventually, Project Gotham 2 came out, and I immediately noticed that it ran at 30fps. The graphics were improved, so the frame rate was cut. Was let down at first, but eventually I ended up liking Project Gotham 2 more than the first game because it was simply the better overall experience.
Then Project Gotham 3 came out on the 360, and was easily the best looking in the series AND ran at 60fps. But I didn't like it as much as Project Gotham 2 at 30fps. Won't get into why and give a full review, but yeah, there you go.
As far as Nintendo goes, I've many of their systems, but it's been a while. Last portable I had was a DS and a DS Lite upgrade, and the last home console I owned from them was the Gamecube.