For a movie, they would need much more detail than even a good RMP product - consider the screen resolution! Also, the cost of the models is peanuts compared to the stars' salaries.

As for costing your time in making a model, this only adds up for professionals. I do make a small amount of money from commercial work with Poser, but if I compare what I make per hour with what I charge IRL for my time, it's laughable. I do it because it's a hobby and therefore fun. The fact that I earn pin money from it is a nice little extra, but not my main motivation.