Adding to what Llamatron says, there are loads of films that do get made but don't manage to get distribution deals.
A lot of these may get a release on DVD, but with only a few exceptions, they were all made as cinema films.
The cinemas in this country are mostly owned by the American studios, so they want to show the films that will bring them the biggest return on their investment.
To be fair, the amount of re-makes are a small percentage of the films made, I think it may be that you notice them more because you are familliar with the subject.