Re: Machine gun preacher... no wide release??
Take my words here with a large grain of salt, but in limited release it's opening in choice locations, which hopefully give the distributors some idea on the film's gross potential. A slow roll-out is intended to build word of mouth, and keep adding screens as you go along, (good examples are Midnight in Paris, Slumdog Millionaire, The King's Speech) but they need encouraging results from a large average per screen for the roll-out to continue.
You can see on http://www.boxofficemojo.com
that MGP started out with just over 11k per screen in four areas; the week after it added two dozen more and the average went down to 2,5k. With P&A, it wouldn't make fiscal sense to widen its screen count, since their budget on P&A would probably eat into any potential profit.
There's quite a lot of films which distributors think have breakout potential, but after several weekends where slow expansion fails to amp up, the release instead dies slowly (127 Hours, Buried).
I hope my post makes some sense here, but to sum it up: If a film fails to build upon an audience during the first 2-3 weekends in limited release, going wide with the release would probably cost more in P&A than they could recoup, so a write-off is more sensible.
*Here's a nice link on per screen average, where you can see some of the slow releases that succeeded; http://boxofficemojo.com/alltime/weeken ... AVG&p=.htm