Are you serious?
Movies don't just go up to 1080p, that is just the best resolution available for home viewing.
Modern digital motion picture cameras are 4k,which means 4 thousand lines of resolution
(4x 1080p) and film, which most movies are shot on, does not have a definable resolution, but trust me, films clarity is far superior to 1080p.
Edit -looked it up, films resolution is actually listed as being 6k, meaning 6,000 lines of resolution. Even the 4k cameras are often upscaled to 8,000 lines of res during the special effects process. So trust me, tv has a very long way to go to match anything in the cinema, as a matter of fact, if you watched something with only 1080 lines of res on a movie screen, it would look horrible.
Actually no, many times they drop it down to 1080p because it's cheaper to work with. Especially when they first started computer FX it's very expensive to work with a higher resolution. They've done that type thing even as recently as Avatar. Even when they were working with IMAX for The Dark Knight, they did the FX in those parts at a lower resolution and then upscaled it later.
Very few movies would benefit from higher than 1080p. Upscaling doesn't count.