At moments I wonder why I think about these things so much. I'm not aspiring to become a pro cyclist. I'm not training for grand tours, or even local races. And who cares whether I ride in the saddle, or out of it?
The main reason for wanting to improve my out-of-saddle pedaling is to give me some occasional relief from sitting during prolonged rides, without having to actually stop and get off the bike. It also brings a bit of relief to any irritated areas that normally have saddle contact.
It does, however, tire me much faster than pedaling while seated, and I don't yet have the nerve to try it while climbing. It's amazing to see pro cyclists pedaling out of the saddle on long, steep ascents. They've got some tough legs!