To make people more accustomed to the AI generated look so that when they release their next Veo integration to YouTube content creator tools, these videos will stand out less as unnatural.
There's also the on-by default, can't be disabled, auto-dubbing YouTube performs on every video that's not in the single browser's language. The dubbing quality is poor for the same reason, to intentionally expose viewers to AI content.
It's 100% a push to remove human creators from the equation entirely.