The logic by which Kosovo would be granted independence, would also require that the predominantly Serb portions of Kosovo (and Bosnia too, for that matter) be absorbed into Serbia. They can't have it both ways, not logically.
But they are trying to have it both ways.
Has anybody stripped the Sandzak and Presevo Valleys from Serbia?
No, because the Serbs haven't embarked upon an ethnic cleansing campaign there like they have in the places where they have lost territory.
The Serbs lost their mandate to govern Kosovo, and Kosovo is keeping its existing borders.
Its not as complicated or illogical as you're viewing it.