Not to mention that it's such a sudden announcement. I mean, sure, they gave people 3 months notice in advance, but when you consider the scale of many games probably take longer than 3 months to make the decision AND actually make the switch (or make up for the switch), it's cause for quite a bit of harm.

Granted, the majority of people may not be affected by it due to needing to meet a requirement of like earning $200,000 and 200,000 installs at a minimum, but I feel like the once you reach that, it's just downhill from there.

In addition to your example of costing the devs for reinstalling the game, you now have to consider the possibility of a user (or group of users) maliciously reinstalling their games to financially damage the developer. Sure, Unity says they'll have fraud detection for stuff like that, but then it's literally up to the people you owe money to decide whether you should pay more or less money to them.