I don't think their is a need for either Raw or Smackdown to be over two hours. When your doing a weekly show sometimes a little less is better. Ideally, you want your fans to feel like they cant wait to see what happens next week, but thats very tough to do when you are doing 6 hours of tv a week between Raw, SD and Main Event.
With the brand extension basically being dead. I think they should just go back to the old format. Unify the WWE and World title with Raw as the main show and Smackdown as the secondary show. You will have a much better main event scene when you have guys like Punk, Orton, Cena, Ryback, Sheamus etc all going after 1 title.