In response to the precedent with Ubers and HypnoGar, I think that is a somewhat dubious decision that they're just rationalizing in a way that makes it more palpable to the PR crowd. Ubers is not Smogon's all-inclusive metagame (AG is), so it shouldn't get special treatment. I'm almost certain TI shares a similar mindset based on his post in that thread.
Similarly, MnM is not the all-inclusive OM (BH is), so it shouldn't get special treatment.
In response to the bit about MnM's popularity:
In my opinion, it isn't diversity that makes this popular, rather the concept/mechanic itself. That concept is still really good and provides many new opportunities that differentiate MnM from standard play and other OMs. Gen 7 will just be a drastic shift in what threats/stones define the meta, which isn't objectively a bad thing. The concept is still awesome and should draw players without issue if its core players give it the same attention this go round.
Similarly, MnM is not the all-inclusive OM (BH is), so it shouldn't get special treatment.
In response to the bit about MnM's popularity:
In my opinion, it isn't diversity that makes this popular, rather the concept/mechanic itself. That concept is still really good and provides many new opportunities that differentiate MnM from standard play and other OMs. Gen 7 will just be a drastic shift in what threats/stones define the meta, which isn't objectively a bad thing. The concept is still awesome and should draw players without issue if its core players give it the same attention this go round.