I love those theories that they wanted to destroy the Enterprise D because it just didn't hold up well on the theatrical screen. Well, that kind of thing will happen when you have a TV show effects crew working with a fudge ugly 4f model and barely having it do anything. So when the time came to whoop out the 6ft model of the Enterprise D and shoot it in true movie fashion, I bet someone said "Uh, who said this ship wouldn't look good in a movie?"
And seriously, I'd argue that the big D is more suited for movies than television. For one thing, the ship is very wide so that would fit perfectly with the theatrical widescreen ratio. Second, the tools used for making movie special effects give the ship a much richer and more detailed look. The opening reveal of the big D alone is quite memorable as it approaches the observatory, and the way the camera gets really close during the Klingon attack is astounding.