I think it makes sense to get extra XP if you do stuff in certain ways. If a town is under attack, and you persuade the bandits to leave, you should get less, why? Because you didn't solve the issue of 'stop the bandits', you just delayed them from attacking, they'll be back someday. If little Jimmy says 'please stop miss grouchy from hurting me', and you kill the lass, you should get less too, he didn't want you to KILL her! Just to get her to stop, he's a kid. Etc.