That's actually a big thing! I hated it that the PS3 required the console to be powered on to charge the controllers.
Same here. I only had a 3 foot USB cable for charging my PS3 controller. So whenever it would die, I'd have to sit on the floor directly in front of my TV (instead of on the couch)...or stop playing for a while. Both were a little annoying. I'm glad they added this little feature.