To begin with, Mists of Pandaria wasn't a popular expansion, so that alone doesn't help the problem: x1 servers already has low population (not everyone plays during peak), it would be a massive waste of time and money to open up a fresh realm for MoP in my opinion. Other than a slap to the face to people who already had so much time and effort into accounts, Frostwolf inherently has low population for many reasons but not limited to the low quality of the server, especially end game content with most things pushed past passable. Which, again, in my opinion content that wasn't fully fixed shouldn't have been released. Just because people can kill it to therefore follow coin store item release policy doesn't mean it's acceptable behavior because content that works will always be appreciated no matter how long it took, but if things are broken and messy upon release day that doesn't feel okay to me given the claims to the alleged polish and professionalism that attract players.
The current status of the server doesn't allow for lower rates anyway, as many quests are bugged and whether in your favor or otherwise at times, there are enough to get you by.
I'd probably change expansions if they introduced another realm, MoP or not. Though to be honest I'm already looking elsewhere because playing on Frostwolf has left a bad taste in my mouth along with a few negative observations from being a long-time member.