I think they are looking at it from a large scale business angle.  They are waiting for sales in Animal Crossing for the 3DS and the boosted sales in the 3DS to drop, once that has finished, then they will introduce it for the WiiU and see the sales for the WiiU version and a boost for the WiiU system.  If they launch them together, people will buy one or the other, and probably not both.  With the seperate launch date, they can get people to buy two games and two systems instead of one.

I was just playing today, and here are constant problems.  There are so many goals scored that you just can't do anything about it.  Rebounds, because the defense AI still isn't smart enough, opponents can sit in front of the net and smack in rebounds with ease.  The same thing with One Timers, there are too many times when the opponents are just hanging around in front of the net and Def does nothing.  Shots are really accurate and really fast, even with the sliders altered for no accuracy, no power, and goalie has max reaction speed, what should be weak shots, are often scoring goals.  Today, I let in most of the shots from the blue line.  They would hit a magic spot in the corner that I as goalie couldn't save, even when I was far or near from the net.  The CPU goalie is playing like Hasek, even though his over all rating is really poor, and I am playing like a drunk pirate.  Finally, the skaters get those shots off with ease.  If you watch actual players, they have to stop the shot, let it settle, and then they shoot.  In the game, they zip a powerful shot off with no settling the puck and no windup.  The mechanics of the game just don't allow for human players to be goalie.