Looking back over the 40 Wii games in my collection, there are few that were cross-platform (meaning PS3/360). Sure, many are 'family' games, which most gamers don't care for, but there are other titles:
(Obviously the first-party, but they're important as well)
Super Mario Galaxy 1 & 2
Red Steel
Mad World
Okami
Endless Ocean 1 & 2
a boy and his blob
Trauma Center: Second Opinion
Metroid Prime 3: Corruption
Little King's Story (looking forward to the next one on PS3)
Another Code R
Zack & Wiki
Zelda - Twilight Princess & Skyward Sword
Kirkby's Epic Yarn
Boom Blox 1 & 2
Donkey Kong country returns
Xenoblade Chronicles
I'd love for those games to come out on PS3, but it's unlikely - LKS is unusual in that respect.
Being able to play them, and the sequels, etc. in 720p/1080p is reason enough for me to buy the WiiU. Being able to play the existing titles on the handheld screen is a bonus.
There's so much talk about 'next gen' except nobody can really define what it is. The next round of Sony & Microsoft consoles will be behind the top-end PCs, and resolution isn't really what's missing from graphics (a big hint here - how often do you find yourself watching a bluray movie, and thinking it's a bit **** at only 1080p/24
),
UE4 will be excellent, and the PC will be the place to go for that. I'll likely get a PS4, as I like a lot of the Sony exclusive franchises. MS give me nothing, as I don't care for the Halo or Gears worlds.
Today, I've mostly been playing Crush3D on the 3DS. In a bit, I'll be back (again) to Dragon's Dogma on the PS3 and next week will be Lollipop Chainsaw, followed by Lego Batman 2. I'm also playing through Dead Island and Risen 2 on the PC.
Variety, etc.
I really think some people are going to be disappointed quickly when they realise how far the 'next gen' doesn't really jump from what's possible already on PC. At least there are plenty of new gaming ideas coming out, and the animation/AI are improving again.