It's a playstyle thing. MM can turn a game if played well, but if you are after just the numbers DOT trees win every time.
My MM regularly is in the top 2 in wz's damage if not in guard mode.
MM has a nice mix of team utility benefits and single target damage that is great for an integrated team, but can be spotty in terms of utility if solo PUG'ing.
Also, there is a steep learning curve to go from OK numbers to good numbers, which has more to do with positional awareness, than which key to press. There is also a 'most efficient' rotation to use against each AC, which also adds to complexity.