I think the issue is 90% of the population on Dynamis are made up of alts trying to get a house when they couldn't do so on their main servers.

So after finally getting a house, everyone just went back to playing on the main on their home servers, leaving the remaining 10% of actual new players diddling their thumbs waiting for the queues to pop. When that didn't happen, they too DC travel to other data centers to get working queue which exacerbates the situation even further. I honestly have no solutions for this problem unless SE decide to take drastic actions to even the server population by designating all old servers as congested, leaving people with no choices but to create new characters only on Dynamis but that would never happen.