Meetup was profitable long before Wework acquired it. People aren't bitter about service fees, they're bitter that Meetup is adding friction for _attendees_ when it's already incredibly difficult to get people there.
While I sympathize with this line of thinking, it's a question of value. Meetup is already charging organizers, while providing what is a pretty bare-bones app and mass email service. It's also a change that fundamentally changes the dynamic and incentives of the communities already built up on Meetup.
It's like if your local dry cleaner changed their pricing from $5/item to $1/square foot of fabric.