Mission rotation was already implemented into fight clubs the past, when joker tickets and mini missions first came out. Is it possible they just turned mission rotation off?
Even if mission rotation isnt possible anymore, i would still choose to keep the kill count matches, because its not a mission area and doesn't need the same kind of missions as the main areas of the game.
Also, the map itself will be a mess either way because spawns were changed at some point by the past owners. Now spawning in any location means you have to watch your back 20m out of the spawn point because an enemy can spawn in that location as soon as you leave.
Effectively ruining any kind of cohesion in what ever mode is running because the most dangerous areas become the areas you just spawned in.