Subjecting the brain, an electrical storage medium, to high voltage life generating machinery would have a tendancy to wipe out a lot of memory. With each regeneration, the brain would less of the previous owners. The poor monster keeps waking up in a cloud wondering who he is and where he came from, and more primordial. Dracula knew this and that is why he wanted to swap brains out in A&CMF. He needed a fresh brain which hadn't suffered all the jump start trauma, but was also "lacking a will of its own".