The cynic in me thinks it's a prelude to stuff like BIMI because that lets them add a large annual cost for anyone that wants decent deliverability. It's a way for large senders to use their market position to invent a new industry with a service we all have to pay for. Free money!
Does Google even sell BIMI compatible certificates? I don't think they're making any money with that protocol.
BIMI does solve some issues with DKIM, so I can see why Google prefers it. Requiring what should be a minor fee for any company to do bulk email will also make it difficult to set up a thousand different spam domains.
The cynic in me thinks it's a prelude to stuff like BIMI because that lets them add a large annual cost for anyone that wants decent deliverability. It's a way for large senders to use their market position to invent a new industry with a service we all have to pay for. Free money!