Unity is an engine primarily used by mobile app developers; it’s their biggest market. Indie game developers are basically just collateral damage, for this kind of a pricing change.
Mobile apps are all about massive scale (millions of installs) and ungodly amounts of revenue. They’re going after large mobile developers, not small studios. (I’m not saying small studios won’t get affected, I’m saying Unity is focusing on the big dogs - potentially at the cost of pissing off unrelated folk for no financial reason)
The per install costs don’t kick in until you’ve made half a million dollars in revenue, and a certain number of installs.
Also, you literally can’t build these apps with other engines as ad network integrations don’t exist for them. So it’s not like anyone has a choice: it’s Unity demanding to be paid more as they’re the only viable player in the industry.
Makes good business sense, though I think they should increase the revenue point of the free and personal tier to a million as well, just to put the minds of indie devs at ease. No point freaking out unrelated people.