Sorry, I didn't mean to compare the 3DS (which is lower), however the crux of your post is still what I debate. You're saying here (bolded) that you wouldn't benefit from a 720p screen over a 480p screen due to holding the unit 30 cm away. There is no way that you wouldn't benefit from 720p at that distance.
Not only that, but as liger said - that data is bogus. It has been used in similar discussions before and it's simply untrue. The differences between many of those resolutions are really obvious even at far distances.
@Jonnas fair enough. I personally wouldn't go with 480p on such a screen size to get 60 fps due to how crappy and antiquated it would look (not to mention the unit is full of titles that would not benefit as strongly as some other genres would). I know some people would like 60 fps, and I would too, but I think Nintendo shouldn't limit themselves there to get it. If anything, try for both, but keep the graphical power at the level of the GameCube.
I mean, it's not to say they couldn't do 60 fps with 720p, while not pushing the system to its limit (like Link Between Worlds didn't push graphics but was 60 fps).