I think they know that their market is as a heritage band. Play the hits, put on the classic tried-and-tested stage show, and look the part of classic Kiss.
They've done the unmasking, moving with the times musically, looking for acceptance as musicians by changing their look and sound, etc.
Now they know their role, and their place in history, and they are happy with it, as it's this that brings in the money.
There's no market for half their products without the make up being involved, so I don't see it coming off again untill maybe a very final show when Gene and Paul eventually retire...
Plus they have to realise that they are wrinkly old men now, and the make-up hides that too!
Niv