Uh, in dos and Dos2 you got xp for exploration, solving quests, discover secrets and using dialogues and stuff like that. You can go back at the end of the act and kill everyone for extra xp if you want to but it´s not mandatory.
It would be great if you also have xp for exploration, uncover secrets and the use of skills ( dialogue, thievery, arcana and nature checks, perception and investigation,...) and things like that. I expect we would have those at full game release.
