I agree with you that MIT license is very permissive for decentralized project like Bitcoin, but I'm very curious to know that why Bitcoin core wasn't launched in public domain? Let's suppose if the core was launched in public domain then wouldn't that be more decentralized because in that case no-one, not even the developers could have any control over it, and anyone could easily modify and add new features to it without any permission.
Anybody can change anything about the code and do whatever they want, there is just "filters" they have to go through to get them merged into the reference implementation and of course there is a community they have to convince to accept those changes.
I think the Creative Commons Zero license would be even more permissive and easy to use than the MIT one, and that license doesn't require the attribution to the original creator. If the reason was permissiveness then both public domain, and CC0 license would provide more freedom.
CC0 was released in 2009 which is after Bitcoin's release while MIT license existed ever since 1980's.
https://en.wikipedia.org/wiki/Creative_Commons_license#Zero_/_public_domain