I've always been on the fence about this topic, on the one hand i like solving things without resorting to violence, but i always found it odd that my characters becomes stronger/hardier, better at fighting or casting magic, without actually doing any of it. I actually feel that it suits my roleplaying better if i don't get any Xp from it. it's kinda like taking the narrow path, Sure I might not get any immediate rewards or riches from it, but my soul is kept clean.