I believe it is to make sure that the product remains compliant with the data guarantees that Workspace provides. You aren't paying for the latest and the greatest features, you're paying for the support and compliance guarantees your business expects.

because paying users don't want features quickly.

companies want features gated behind controls, they want audit trails, compliance, SLAs, integration with their admin consoles. and they want some certainty that the feature won't change too quickly.

i will never understand why people keep using workspace accounts for personal use, and then being surprised when features hit those accounts more slowly. this is how it's worked for 20 years, it's not going to change. if you want earlier access, create a gmail account for your personal use.