I'm very unsure as to what benefit if any at all we would get from a big screen Doctor Who.
The budget would have to be considerable, which means the Beeb would either have to go into partnership with a big studio or, more likely sign the rights over to a big studio.
If you tried to do it on the cheap it would be naff.
The franchise from the Beeb point-of-view is pretty healthy now and making money hand over fist.
If they handed it over to a big studio then the studio would probably want casting and script approval. People have complained about the tv movie but at least the Beeb had some input into it's making. With a big studio in charge I doubt they'd get much if any. Who knows what sort of hideous travesty we would end up with then?!!
Then you have to appeal to a large enough market share to get the studio's money back, preferably several times over.
I can see it now:
Tom Cruise IS Doc Who!
co-starring Alan Rickman as Davros
Watch out Daleks this time it's personal.