That's pretty much the standard for films now. They basically pick a date and see if they can film the entire movie and edit everything before then.
Personally, I don't know when this film SHOULD come out to be successful. But I gotta say, while I'm glad they're not rushing into anything, I really don't like a winter month release. I hate seeing movies in winter, and half the time, I just don't even bother seeing films then. It's too cold (think about having to dress warmly and then sit in a warm, theater in uncomfortably warm clothing for 2 hours), and that's even if you can get to a theater in case some idiotic storm comes up. Trust me... I missed a LOT of movies because I just couldn't get to them.
But if they feel that's a successful date, I hope it is. I personally wanted to see it on a warmer month, but the summer movie season would probably shellack it, no thanks to multiple blob-busters released at the same time (which is why everything's doing terribly, except for Iron Man and Shrek this year).
I just hope that we don't see Muppet Show season 4 held out until that date myself. We've past the 2 year mark since season 3. DVD's will be completely obsolete by the time we get Muppets Tonight!