Square/Enix has had a rough year. The last Final Fantasy(s) didn't really get all that much praise from the public or the press and the former industry giant is hurting- hurting so much so that they've delayed one of the most hotly anticipated games of 2011, Deus Ex Human Revolution.
SE has told Kotaku that they want more time to polish the game up and basically make sure it's up to snuff before launch. That translates into an April 2011 time frame instead of the previous quarter 1- which was pretty ambiguous anyway.
Extra time can't hurt the project but it also doesn't guarantee anything great if there are already fundamental flaws in the game. At the end of the day, it's way too late to make alterations at the base level. Anything like that would seriously move the release date and muck things up even more for the company.