Something is very wrong here. Having JJ direct Star Wars has nothing to do with artistic preference. This is about getting OUR money, boys and girls. I'm thinking they're trying to get the most out of the science fiction buck these days and trying to turn Star Trek fans into Star Wars fans and visa versa.
They want the two fandoms to be interchangeable so both studios get the most out of the sci-fi fans wallets.
I dunno. I've got a very bad feeling about this.
Honestly, I don't see the big deal. At any given point, creative folks are going to have multiple fires in the iron and work on a variety of different projects with a variety of different partners, sometimes even in the same genre. Doesn't mean they're all interchangable.
I mean, look at comic books. The same writers and artists go back and forth between Marvel and DC all the time. Jack Kirby, Marv Wolfman, John Byrne, Frank Miller, etc. Doesn't mean Superman is going to turn into Spider-Man and vise versa.
In the end, it's just a matter of logistics. If you can manage two franchises at once, more power to you.