I think a lot of people have tried! The reason EKUs stuck where NCs haven’t is because EKU rules are simple (in relative terms) and OpenSSL didn’t make as much of a mess out of them.

I can't help but read your post as "OpenSSL didn't make a mess of EKUs so the CA/B had to fill that role instead" :/

(I really am salty about the EKUs. In a few years the EKU field will just be useless, due to operational annoyance driving devs to ignore it. Except in browsers of course.)