The issue is that they are trying to retroactively change a license agreement, and doing so in a way that will bankrupt many of their current users.
Charging per install is absolutely insane, and will absolutely be the end of many publishers. Even successful games like Cult of the Lamb are being culled because of this.
It even seems to include, for example, any reinstalls I might do of Cult of the Lamb, which I purchased months ago when it launched. That’s why Massive Monster’s response was to announce they’re delisting CotL to cap costs (and as a protest, of course).
All this says is that they won’t use historical telemetry data to retroactively bill you, and that every user install will only be charged for once.
No one, anywhere, on any thread, is against Unity charging more. Many of us are already paying Unity a significant sum.