It's certainly a good idea to get up off the saddle to navigate rough patches. But that tactic has its limitations too. If you've got loaded panniers etc., then getting your own weight off the pedals still leaves a lot of weight on the rims, racks, etc. Plus, out in the real world, there can be a lot going on, e.g. traffic and road signs and beautiful landscape etc. etc. so it does happen that one encounters a pothole by feeling it before seeing it.