To me it wasn't important that Wii didn't run UE3, that's why I just don't care if WiiU doesn't run UE4.
The obsession about visuals seems to be endless here at Gaf...
Might not matter to you, will matter to third parties.
I think both these viewpoints are valid.
As with Mlatador, I'm not personally fussed with visuals. If they are tip-top, great. If they are slightly better than PS3/360, so be it.
I appreciate third parties who invest heavily in UE4 or equivalent tech may not be impressed, but for the most part, those sorts of developers weren't making a lot of the games that appealed to me this gen.
Ideally, Wii U will be capable of supporting as much of the new round of engines as possible. But I'm probably in the group that can deal with it if it isnt capable.