Yes a movie based on the original He-Man and the Masters of the Universe cartoon would be great. I know there was one made in 1987, but this wasn't that good I thought and there where a few classic MOTU characters missing in the film, including Orco. Plus that film wasn't true to the original cartoon series at all.
I'd love to see a new He-Man film strictly based in Eternia, perhaps featuring how Prince Adam first became He-Man, something like that would be good, as this wasn't properly explained in the original 1983-1985 series.