I think the concern is that Unity is failing. Charging royalties is not going to save them, and is going to drive more devs away from the platform (as this arti

I think the concern is that Unity is failing. Charging royalties is not going to save them, and is going to drive more devs away from the platform (as this article shows), so they are going to have to do more drastic things to raise revenue, which will drive more devs away, and so on into the familiar death-spiral. If they can't cut costs enough to get profitable (and history shows this is very difficult) then they're doomed to go through a series of increasingly more disastrous acquisitions (see Yahoo for details). Given this, then the details of this particular royalty structure don't matter. Yes, a freebie game may not have to pay any royalties now. But as Unity enters the death-spiral that will probably change. Or there will be mandatory malware shipped with the engine. Or some other craptastic revenue-generating idea will mess with the game. We can expect relatively frequent, drastic changes to Unity's licensing as it tries to escape its fate.