I'll send you the white paper Alex and Morgan wrote. Here's the nutshell version for now:
Gaining a new skill from a Neuromod works similar to the way your brain creates new memories. In fact, it's impossible (for now) to separate the changes the mod makes from normal memory formation. So if I want to strip the Neuromod that makes you play piano like Gustav Leitner, it'll reset your brain back to the moment before you first installed it.
They wanted Morgan's mind pristine to receive the prototype Neuromods. That means going waaaay the hell back. Hence the apartment sims. Yus are dedicated to their science is all I can say.