Being able to do it for more than a few seconds would be helpful on very long rides, when sitting on a bicycle saddle for hours starts to take its toll. I think maybe I need to get used to the way the bike sways while I'm pedaling out of the saddle. It feels like I'm about to go wobbling all over the place. I also don't yet seem to have the leg strength for prolonged out-of-saddle work.
Another thing I didn't get up the nerve to try for at least a year: riding on the drops. The first time I put one hand on the drop, I nearly veered out of control. It took a few tries to figure out how much weight I could put on the drops.
Now I'm a good deal more comfortable riding on the drops. When I'm wearing the Camel-Bak, I can actually take my left hand off of the drop long enough to grab the drinking tube and put the valve into my mouth! So far I haven't tried to pull the water bottle out of its cage while staying on the drops.
But riding no hands? Not yet! As Selene Yeager says in at least one of her books, let your skills build at their own pace; don't ride over your head.