You must be playing a different game, MM on beta is as bad as it can be. You should try doing some mythic dungeons where you need to keep moving from aoe and other shit. There are fights where you cannot cast more than 10 aimed shots in the whole fight because you need to keep moving all the time. That means you do roughly 100k dps which is absolutely pathetic
There is no reason to bring an MM over a BM hunter for mythic+