Disney has taken another safe bet in acquiring a franchise with proven film potential, as Marvel's stable of superheroes have been churning out blockbusters for the past decade. Simply making Marvel movies by itself was playing it safe creatively, and Star Wars is another kind of sure-thing property for them.
This is incorrect. The recent Marvel approach to super-heroes has achieved a level of success that supers movies had not seen before. For every success (Batman 89, Donner's Superman, Raimi's Spider-Man, and Singer's X-Men), there were several big budget flops (Fantastic Four --critical flop at least-- Daredevil, Electra, Superman Returns (critical flop), Green Lantern, Lee's Hulk, etc.
Marvel seems to have found a hero formula, but DC is still looking for one.