I can understand your suggestion, but I personally wouldn't like to have such a button in the main program due to me being clumsy, as long as we don't have a REDO FUNCTION (!). I bet, I would press that button accidentally and therefore would destroy my long hours of (unsaved) work. BUT there are allready plugins out there which can do some sorts of randomization and/or look-mixing, and there might be current or future VaM menu overlays for a more simple VaM usage that have a function like this.
By the way, this is not as trivial as it sounds: You can have thousands of additional morphs in VaM, and most of them would look extremel stupid when mixed together randomly. Therefore you will probably only have some basic looks that will be blended into another, and the quality of those random looks will be strongly depending on the quality of those templates.