The uncanny hands-but-not-fingers movements they all do really bothers me. Their hands flop around but stay completely limp. Like they're robots who heard that humans move their hands when talking but don't have any fine motor control.

Yeah, the biggest problem is really that they all have the same approach, so these specific details stick out more through repetition. They don't let their presenters speak in their own voice or in their own presentation style. It's ironic for the company that made that 1984 commercial. The attempt at using different speakers to add variety actually ends up doing the opposite because the similarities become even more evident when a dozen people all behave in the same way.

This has been a thing for all tech companies for years.

According to what I was told by some FANNG people (I've never worked for them myself) some employees were/are were sent to public speaking classes after being hired specifically to teach socially awkward programmers how to talk on stage, and this is what they teach them, weird hand movements and all.