Honestly with the WiiU, I don't see a reason to have to Mod it in my case cause my Wiiu main controller dies too quickly and it has severe drift. We only have Mario Maker 1, the Starfox game (and the other minor one), Splatoon 1, Hyrule Warriors, Resident Evil, Smash 4, and that's it on the top of my head. I personally didn't use the online on these games (but my sister did with Splatoon 1) and this alone coupled with the fact that most of the other games I didn't mention didn't really have online features on them.
What can you do with a Modded Wii outside of getting Wiiu games through different means even if it's hard as heck trying to do so