I think players on Dynamis really need to stop hopping to other data centers to run their roulettes/raids etc.

If everyone does that, the queue times get exponentially worse for those who remain on Dynamis, which in turns force them to do the same thing as well. This perpetuates a vicious feedback loop where eventually Dynamis is just a dead DC. As bad as Materia is, there's at least the consolation that the players have to build up a community and run events on the DC itself instead of taking the easy way out and abandoning the DC.