Aggrend made a comment on the wow community council section that basically said their priority are servers that have existed for years because these new servers are more likely to die off anyway, where as the megarealms will not.
Post #14
" So the fresh realms are a very unique situation and we want to be extremely careful about adding more realms. Adding a 2nd fresh PvP realm is very very likely to do one of two things:
1. Lead to both realms being unhealthy in the long term.
2. Essentially guarantee that one of the two realms becomes the “horde” server, and the other becomes the “alliance” server.
Additionally, Fresh realms are also much more likely to experience a bit of a decline once the game actually launches. Many people are leveling in fresh now during pre-patch but we expect some number of those players to return to their normal established servers and guilds once the expansion launches. This might be a situation where its better for us to weather the storm, as it were.
Lastly, the fresh realms’ total “footprint” of players isn’t nearly as large as a server like Faerlina or Benediction. These established older large realms will continue to swell as folks return who may be inactive unless moves occur, which is a different situation than Skyfury is in. While the queues on Skyfury are long, they aren’t as long as the other queuing mega-realms. If everyone in the queue for Benediction went to another realm, that realm would be queuing as well. That queue is more than double the capacity of the realm. If everyone in Skyfury’s queue went to another realm, it would be a fairly busy realm, but not nearly full. Skyfury and the 2nd realm may not survive that division long term.
Fast reactions to immediate problems are part of what got us here, and while our goal is to get everyone into the game as soon as we can, we also want to make sure Fresh realms are a long term success as well. We want to be extra sure that the only option is to open a new fresh realm before we do so."
-Aggrend, WoW Classic Game Producer