Wii U needs an update to play Wii disc games

[Barozi]

considering that almost 30m 360 gamers don't have an online account (and therefore don't have their console connected to the internet) it's going to affect a large number of future WiiU owners.
On the other hand if you really want to be able to play Wii games on your WiiU you should get it done without that much trouble.