just going to bring up interviews from e3 from miyamotto and them talking about mario quick
we have 2d mario, 3d mario and 3DS mario, and a simple task ahead of us. Jump and hit the block to get a mushroom, or land on the same said block from above.
2D: easy as heck, basically anyone who can pick up a nes controller can hit a block
3D: can be super hard and miss countless times and have to rejump, judge, ect. I dont' know how dumb i have felt in past not able to hit a block just sitting there in open. And landing takes quite the skill and getting used to.
3DS: now with depth it is said to be insanely easy and back to old 2D style.
Same has been said about like pilot wings or star fox, how in 3DS it is insanely easy now to go through the rings.
Best example since same game is star fox, now did they dumb down starfox? No, it is just easier to do something not because its easier task in itself, but because we can percieve it better. think of deku shrubs in zelda shooting nuts at you. Take a room in 2d with 4 of them in it, and a room in 3d with 4 of them in it. I could dodge all day in the 3d room and not be stressed at all, in the 2d version i would be struggling.
Some things that are hard in 2D are easy in 3D, and vise versa.
