You might as well ask why do KFOR troops have anti-tank weapons at their disposal or why there are Main Battle Tanks operated by KFOR. Actually, that is a good question. Why would peacekeepers need MBT's? I could understand them having heavy tanks and such while the Milosevic government was in place, but now that a pro-west government is running Serbia why does KFOR still regard the Serbian military as their number one threat, when it's painfully clear that their only threat comes from small lightly armed groups of terrorists? KFOR appears to be too well armed for a peacekeeping force but not armed well enough to resist an invasion from Serbia. The type of job they need to do now doesn't involve fighting against a real military, but defending people and buildings from terrorists, etc.
On the MBT side I was still thinking of the force structure during the first two years. KFOR underwent a re-structure at the end of 2002.
http://www.nato.int/kfor/chronicle/2002/chronicle_16/06.htm I"n response to NATO Supreme Allied Commander Europe, Gen. Joseph W. Ralston's request for an assessment of force structures and needed changes, COMKFOR proposed to merge four of the brigades into two:
"We have proposed to re-organize our current brigade structure, which has been the same for three years, from five brigade headquarters to three brigade headquarters," said Lt. Gen. Valentin.
The goal of the reorganization is to tackle more effectively new challenges now that the absence of an external threat means that KFOR no longer needs heavy equipment such as tanks and artillery.
HQ KFOR has been working on this project throughout the year."