It's easy to say we should have used him more, but we don't know how he would have responded, it could have delayed his development, or gotten him injured.
As far as play calling I think the results speak for themselves. The Vikings offense has scored more points every year since Musgrave got here. No team scored more points that didn't have a good QB on the roster.
Zimmer has also been "linked" to Mike Mularkey and Scott Linehan in recent days. This doesn't mean anything until Zimmer is hired and he announces that Musgrave is staying. So to answer this threads question, yes I still want Zimmer because he is a fiery coach who gets the most out of his players, and that is exactly what this team needs.
Vikings offense by year. 2011 was Musgraves first year here(nfl rank).
2010- 314.9yds per game(23); 17.6pts per game(29th)
2011 - 329.7yds per game(18); 21.2pts per game(19th)
2012 - 336.6 yds per game(20); 23.7 pts per game(14th)
2013 - 344.2 yds per game(13); 24.4 pts per game(14th)
Most of the players on offense are returning in 2014, let them continue to improve, and have some continuity. The plan is working, I really think we are only a good QB away from having a very good offense. A new coordinator means a new scheme and play book, erasing all the progress we have made on that side of the ball.
Let Zimmer focus all his attention to turning the defense around. He can pick his own coordinator and position coaches, and use most of our draft and free agency resources on that side of the ball. He doesn't need to touch the offense at all.