It was possible in Age of Conan and I think it should be possible here also. It won’t result in clans constantly changing server because not everyone wants to pay several times for this service, Funcom gets a bit of money without having to do much for it, unlucky players who leveled up on inactive servers get a chance to enjoy the game on a more populated server.
I get that a lot of people are against it and I understand why, but there needs to be a middle ground because playing on a desolated server is boring if you want to interact with other people in the game. Getting to lvl 60 takes a long time and involves a lot of grinde, people shouldn’t have to go trough that several times.