I really don't think WWE should end it. WWE has made more profit off of this than the pre-draft times. As HWarrior put it, we do get to see more wrestlers on the shows and as a result those wrestlers can get more exposed to the TV time. Without this brand extension, pretty much all the younger guys would get buried by the more "important" guys as far as TV time is concerned.
If WWE were to end this extention, they should of ended it within 6 months of it's existence. Now, it simply too late for WWE to take such a drastic step. WWE just would lose too much momentium if they were to get rid of the brand extention now.