>subsequent removal to obtain the supposed "original, non-derived" form

Also called a "back-formation". FWIF I don't think the existence of corrupted words automatically justifies more corruptions nor does the fact that it is a corruption automatically invalidate it. When language among a group evolves, everyone speaking that language is affected, which is why written language reads pretty differently looking back every 50 years or so, in both formal and informal writing. Therefore language changes should have buy-in from all users.