SmackDown has been a great show since the brand split. They showcase better character development, better story-telling, wins and losses actually matter, etc. Despite the high quality of the show, look at the Backlash card. There is no way you can stretch that over 3 hours.
I've got nothing against the brand split. It's worked out so far. But if they are going to do brand exclusive PPVs, they need to make them 2 hours. I don't see why not. Maybe slightly longer, it would still be ahead of Takeover events in length and those are so top notch that it shows you can put on an amazing show within that time-frame.