But "optimised" 50hz games on Wii U are compromised twice over. First they have to skip every 6th frame to get the original speed, and then the Wii U duplicates every 5th frame outputting the games at 60hz, adding even more choppiness. So the games are actually choppier than we remember them. Incredible really.
Actually I'm not even sure how they optimise these games anyway. Do they just speed up the gameworld and keep animation frames for characters intact, making character animation slower, or do they skip frames for everything?
Depends on the game. It's much easier to change a polygonal game to 50Hz because it's trivial to work out interpolated positions relative to keyframes. You can't do that with sprites - the ideal solution but a lot of work is to redraw the sprites based on the new timestep, but that's generally not realistic. One method I've seen used - by Ikaruga on the GameCube - is to skip one frame of animation in every six, which results in a subtle jerkiness in the animations but retains smooth gameplay speed.
Edit: holy hell, Swype! Corrected trimester to timestep.