We have been down this road before, but since you asked.
1. Brooks wanted to film a faithful adaptation of the stage musical for people who never got to see it. While those of us who have seen the stage show may have already known all the punch lines etc., this movie was made to capture the performances of the actors who did the original roles on Broadway(only wish Cady Huffman and Brad Oscar had captured theirs).
2. In the genre of the old fashioned musical movies, the film was done with a lot of closeups, rich color and over the top performances (again this was what Brooks wanted - not the mark of poor direction by Stroman). You may not agree with his choices, but then it is HIS money AND Universal's money (who by the way was very happy with the returns.
3. The movie is still opening in a few selected countries but in U.S. and international release and with DVD rental returns alone (WITHOUT including DVD sales) it has already made back its investment. It was never intended to be a huge movie and god knows movie musicals will probably never bring in the big bucks again. But it didn't TANK, as people are prone to report. It did quite well considering Universal didn't do much to promote it.
"Life is a lesson in humility"