Colorado has no skills purchase premium active, while DK servers have. It would be unfair to migrate characters from a premium to a non-premium world.
Well if you spent 400.000 nuggs on skill points yes, it can be unfair, but we no longer spend so much money on skills, while sets giving use many more points. This premium rule was always a bad idea, nowadays it became worse, because it kills old servers what still have potential for activity.
Like, what happened with v1. And you know what I mean. If we want to keep this game long enough just let playable servers get some fresh meat, and everyone will be happy. Those who can migrate, can find an active server, and those who working still to keep a server alive, can have some new faces who are capable doing tasks.
Forget the premium "rules" or just change it on older worlds. Historical reasons aren't relevant anymore