I personally like the decision! Non free addons are annoying.
I think similar battle was done with regards to wordpress plugins where ultimately plugins CAN be sold but must comply with GPL.
The difference though is that many WP plugins are SaaS with core features executed on remote server, so GPL or not, they got away with API keys and the actual code is sometimes not even disclosed.
I have a different view… (that probably nobody here will agree with)
I could make an addon under whatever license I want and sell that to customers, I would not break any license, as my work is not distributed with Blender. It’s the user(s) that voids the GPL by loading that addon.