I am in full agreement that roleplaying sessions should be worth exactly as much, if not more, as a purely combat base system. However there is this slippery snake of a thing called participation. Who is entitled to experience? If the party fights a giant we are all in agreement that anyone that was in a position to get squished deserves at least a portion of exp. The lion's share goes to those that fought intelligently, innovatively, and stayed in character.
If a party is in a bar and needs to get information, much like a fight there is a matter of participation. The guy that gambles with the locals and passes drink around to loosen lips earns exp. The guy that takes the bard aside and chats him up about the region gets experience. The gal that takes a barnaid to the loft for a bit of tribbing and milks some directions from her teet gets exp. But what do I give the guy that picked his nose? Even the ass that starts fights with dwarven bouncers gets a nice ass kicking and exp. The guy who'splayer is staring at his cellphone doesn't deserve shit.
Roleplaying sessions are harder to gain exp because the objectives are useually less clear. Fighting is easy, thinking... well, yeah.