You think Nintendo only slightly improved their games? Really? Sorry, but Wii to Wii U is a bigger jump than PS3/360 to PS4/X1. The Wii U console may be the weakest by far, but its still a large jump from the Wii. Nintendo certainly doesn't reinvent the wheel with their iconic IP's, but at least they don't milk the consumer dry with yearly releases of the same games. The biggest games so far on PS4 and X1 are prettier versions of their last gen predecessor. Assassins Creed, COD, Battlefield, Killzone Shadowfall, The Last of Us and so on are little more than prettier versions of games they have been making last gen. The gaming market as a whole hasn't exactly strayed to far from the tried and true product. I would venture to say that the only real selling point for X1 and PS4 is the better graphics, the games arent revolutionary in any sense.
Wait what? Here's Nintys list...essentially Mario, Mario, Luigi, Smash Bros and Zelda.
http://en.wikipedia.org/wiki/List_of_best-selling_Wii_U_video_games
And on PS4/XBO we have Destiny, Watch Dogs, Dying Light and Titanfall thank you very much.