Monster Hunter Tri is for Wii, and yes, it supports Wii Speak, but Wii Speak is not very good. It's a room mic, rather than a headset.
Monster Hunter 3 is the new game for Wii U.
Anyway, my point was that a cooperative game like Monster Hunter is exactly the kind of game where voice chat is necessary. Cooperative games without efficient communication are difficult. You see it all the time with PC games; it's so much easier to just say "let's go around the side" or "I'm going to CC the guy on the left" than it is to take your hands off your mouse/controller and type it. Add to that the fact that the Wii U doesn't have a keyboard, and communication becomes even harder.
People are saying stuff like "just use Skype!" Well, Skype is great, but what if I'm playing a game and I don't have some of the people I'm playing with on my contacts list? It's nicer to to just have integrated voice chat. The people I'm playing with are all automatically on the call. It's effortless. This kind of thing is great for co-op games and fighting game lobbies where there's a lot of spectating.
I get that people have bad experiences with voice chat in games like CoD, but that's not really the point. Integrated voice chat is a thing that 360 and PS3 have had for years, and 3rd-party developers simply should not be required to roll their own solution after all this time. The console should provide a standardized voice chat infrastructure that all developers can utilize. It's just extra work that the developer shouldn't have to do.
Does Wii U suck for not having it? No, definitely not. But it's just one of those things that the console really should have, and just another thing that Nintendo is behind on.