It may also be a case of people you don't want as your customer. I can only imagine that someone with this kind of attitude would use support resources very heavily if they had access to paid support. Maybe not to the tune of $15k, but who knows.

Doesn't necessarily have to be that high. It's more that they are trying to earn their revenue for actual game publishers of all sizes.

Other than the particularly small scale operations (someone's side project, etc.) if the product hasn't hit $3000 revenue in its lifetime, even small/medium sized business would be fairly troubled in the standpoint of sustainability.

It's an issue of not being able to compete with Unity any other way too. Small developers that gain experience with your engine sometimes become big developers, who are going to be used to your engine. Makes sense.