Most of these developers are either clickbait developers who shouldn’t really deserve a vanity URL, or haven’t applied yet. Both of these are really their own fault.
This is a good point, but devforum members are a lot more likely to be trust-able than regular users.
The developer forums have an age requirement of 13 – not every respectable developer with a successful game is eligible to be a member. We can’t reasonably expect every developer to apply for the forums either.
There’s no need to risk “hopefully they’ll be trustworthy” over a proper review process. We won’t be exclusivising features – sorry.