I’ve whined about this but from the other side. That is, I want Fully Qualified Variable Names (FQVN), not just prefixed with the role name. The fact that I have three distinct roles with the same name - one stand-alone and two in collections - makes a role-only prefix not particularly helpful. (It wasn’t my idea! I just implemented 'em, honest!)
ansible-lint will complain if you pass un-prefixed variables in a vars section of an include_role task. But it can’t really complain about a role using variables that aren’t prefixed; it has no way of knowing if those variables are unique to the role or if they come from elsewhere (I’m guessing).