Given how hard they're trying to get people to care about Mac dev again - as with for example the directx to metal converter they want gangbusters on - it's a sensible & good move.
They also have a public beta in July.
If they want people to care about mac dev they should get rid of the fee entirely and supply build tools for Linux/Windows. At the very least CLI tools that can perform the actual compilation. Cross platform compilation should be possible, especially for CI but also to reduce friction of onboarding new devs.
It's absolutely ridiculous that you have to pay to add value to a platform.
Thankfully osxcross[0] is already a thing and does already work fairly well.