It's just a hunch, but I think almost every major change Google has made to the service for many years is in hopes of reducing active users. It's why I hung onto my hotmail account as well, even though MSFT is doing the same thing in slightly less agresive and dramatic ways.
Gmail storage being reduced with a subscription service suddenly being in place, when it's vitally linked to years of saved user data on phones is a clue, so is the fact that both Gmail and Hotmail don't clearly show originating emails fully on messages so that users can double check identities of email senders.
We're in an age of extortionware with absolutely no consumer voice nor congressional defense, and even though subscription fees seem low right now, they'll only increase as users complain, and there will be no choice but to submit to it all.
I don't really get spam, because I signed up for their advanced storage feature, God have mercy on me if I ever decide to switch to iPhone, because most phones no longer support SD cards.
I think my next move will be to downgrade to older hardware, and to avoid all of the great new tech that serves their interests more than me. I'm really worn out on the festering parasitic behavior of these companies, it's a trap.