In MMM's current state, what's the difference of farming the drops off some other NM in the vanadiel to farming it off MMM?
You don't need to collect marbles any more and that was the only hindrance when it was first released.
Either way you're gonna get shitty drop rates, and if everyone can access it'll be heavily camped (for a while anyway), or you end up with some BCNM/ISNM equivalent - but that's no different to buying a maze off Duplidoc. The Goblin voucher is the only slightly different thing, but the reward system seems no different to doing FoV Elite manuals.
In general, MMM events really are just re-hashes of existing content. However the difference is, you have 2 methods of getting to beat it if your group has trouble. 1) Do what people do for other mobs and try and try again till they get a strat or 2) Make your own maze and make the monster easier. If 2) were an option with AV, you can guarantee it would be taken.