It's stated so in loading screens and looks like most of players try to keep their creations alive to level them up. I doubt this is actually useful.
You see, they get skill points, yes, but you can't use that without increasing essence cost! I reaaly don't think 2 pumped-up drayks can be even close to a bunch of five with 2 exra int only I've used to smash through the game. Besides, trying to keep creatures cancels out absorb usefulness and doesn't let you to explore all of your shaper abilities to the fullest extent. So, why is everyone so hanging to their pawns? Can there be an explanation?