This strikes me as a problem with the widespread dogma that it has to be open source (OSI approved license). It doesn't.

If you want commercial users to pay then pick a license that makes it so, it can still be source available and free (as in freedom and/or cost) to non-commercial users.

> The maintainers are now free to respond to complaints with "you need to pay us for us to care."

If you are a maintainer of an open source project you don't have to care about complaint and you can absolutely say that you need to charge for your work in reply to requests. In fact that has always happened.