I love hearing about your sci fi writing process.
Could it be that by erasing people's memories, it also erases their understanding of the social-cultural norms that the control regime has controlled us with? And without groupthink and conformity, the control regime would have less power. Maybe the aliens want to empower the people to overthrow their own deep state government ;) If so, this could empower the people to rise up against oppressive forces.
Although it sounds like you're going for something a bit less positive :)
Hmm, I don't see why ETs wouldn't want to oust the control regime, so you might be onto something: )