Peacekeepers have a lot in common with the police. Both maintain some written text: the peace agreement or the law. And both have the authority to use force, but are supposed also to use persuasion to achieve conformity to the peace agreement or law.
If one analyses the peacekeeping missions in Bosnia and Kosovo it is easy to see that something has gone wrong. They are not real peacekeeping operations but something somewhere between peacekeeping and a colonial occupation.
Take Bosnia. The Dayton Agreement was rather clear. But instead of just maintaining it the internationals let themselves be convinced that Dayton was not good enough and needed improvement. No wise cop will not allow himself to be drawn in a discussion about the validity of the laws. He may be flexible on details, but they will not allow you to undermine the core of their mission. Unfortunately what happened in Bosnia.
In my opinion the internationals (both EUFOR and the high representative) should restrict themself to maintaining Dayton. Any discussion about independence for the RS or abolition of the RS should be discarded with a simple "that is not in Dayton".
In Kosovo the situation was even more extreme. Resolution 1244 was clear about Serbia's territorial integrity. It foresaw negotiations to establish an interim government that respected the territorial integrity. After that final negotiations could be started. Serb diplomats were ready and started soon after the war to hint at several solutions including partition. But the internationals rejected this and instead kept Kosovo in limbo for 7 years - after which they started negotiations about a final solution chaperoned by a partial negotiator and handicapped by Contact Group principles that excluded the option of partition.
Resolution 1244 foresaw a short period of UN rule and as a consequence didn't give extensive instructions on how to rule the province. UNMIK was supposed just to keep things running. When the mission continued for years it got inevitably involved in legislation. This was something for which they had no clear mandate and as a consequence it handicapped them in their peace keeping mission.
The problem with changing your basis is that the mission gets off-balance. The discussion is no longer about how the mission can achieve its goals. Instead it becomes torn by conflicting demands from all sides. This undermines also the agreement that forms the basis of the peacekeeping mission. So instead of promoting peace the mission is undermining it. The effect can be clearly seen in Bosnia where the conflict about status of the RS has poisoned the relations between the ethnic groups and instead of returns has led to continuing departures of minorities.