To be fair, it made some sense to have just one remote used for multiplayer because it came out around the Wii's launch, and not too many people had 4 Wii remotes lying around their house, especially since it was before Wii Play came out (come on! Everybody needs to admit they got Wii Play just for the Wii Remote!) and before the Wii remote's price went down. There were hardly that many reason for people to pluck down $120 for 3 Wii remotes in 2007.
Here's the thing I didn't get, though: having to unlock multiplayer. Ugh.
But, back to your concern for this game, Nintendo Life recently gave their first impressions of the game from the E3 demonstration, and they talk about how the demo's multiplayer was about sharing the Wii U game pad. It is unknown if there will be 4 Wii remote and one game pad multiplayer, however. NL says, "We're not sure if this will stretch throughout the entire package, which will consist of ten or so games, but each of the games in the demo build had only one person touching a controller at once."
From the vib I get from the preview, it seems for the most part, it isn't just a lame "whoever gets the best score wins" kind of multiplayer(though there probably be a mode of that sort for some mini-games).
Shutter, for example, seems to break that mold of multiplayer. As NL puts it, " Shutter works well as a multiplayer game where spectators can watch the main screen for villains and direct the player towards them so that they never have to remove concentration from the GamePad." It is best you read the article yourself to understand the whole context:
Thanks for the detailed info. It kind of makes sense that many people didn't have 4 controllers during launch window, but now SM's multiplayer just feels so limited compared to MPG's. They could have offered controller sharing where it's possible (like in Wii Sports), but it was just disappointing not to have something like the turtle game anymore.
G&W definitely seems to be a major departure from the Wario Ware series. I hope they'll find an interesting new structure for multiplayer.