What was with all the mad scientists in the old toon?

[CyberCubed]

Whenever there wasn't a Shredder/Krang ep, or an ep about another recurring villain like Rat King, Baxter, Leatherhead or the mobsters....the villain usually wound up being a mad scientist.

I've actually lost track of how many different mad scientists there were in the original series. Either that or some other crackpot that was nuts for no reason.

Its odd to me the writers would use these one-shot mad scientists instead of introducing more of those Playmates mutants, but oh well. Some of them were entertaining at least.