So... I read this whole thread, and I felt compelled enough to register for the forums to comment. I figured you guys would enjoy a 'newb' perspective.
I re-subscribed to this game a matter of days ago with a new account - the last time I played being just before the release of City of Villains. Fundamentally, the game has changed very much. The invention system, the flashback system (which I'm not quite able to check out, but I read up on it a bit), and even just all the new content all makes me feel as if I've never played this game before. I'm forced to learn everything from point zero.
As I left the tutorial and loaded into Atlas Park, my chat box was filled with lots and lots of request from either a) low-level characters looking for an AE team, or b) high level AE 'boss farms' looking for very specific members (usually a high level tank). But, as this was essentially my first immersion into the game, I was very, VERY confused at the chaos. Atlas Park, the iconic starting zone, honestly scared me. I didn't know what to do, where to go, or who to talk to. So... I just went to my first contact (Antonio Nash, I believe) and did all the missions he had to offer.
I had managed to avoid the AE up until Lv. 11, when I was on late (like... 1:30 in the morning) and I could no longer find a team or anyone to join a team. I sent a tell to one player, a Controller, asking them if they would like to team with me. Instead, I was told that I should just go join an AE team cause I wouldn't need to do regular missions anymore.
So, I went to join one.
I leveled to 18 in less an hour. I felt so guilty. See, I bought the game to play the game, not to get to the end. As soon as I could, I left the team and tried to go solo some more of my Hollows content. But, alas, I outleveled it. Which sucks, cause I wanted to finish that content.
So basically, my impression is this: the AE/MA/whatever we want to call it has no purpose other than to get to the end before you even know what you're missing. I think most new players are lured into it because of the chaos that it creates in Atlas. And, if they aren't then, chances are someone will say something that will draw them to it later. I can see why the quick leveling is appealing, but I don't really like how it's created an almost elitist attitude among players hardly more experienced than I am.
I don't really like the MA. The only reason I'd go back any time soon is to create my own arcs or play a real, non-farming arc as content and not a leveling mechanism.
But, then again, to each his own. At least you've got one new player that isn't a MA junkie.
Also, sorry if this isn't too coherent. It's 4:30 in the morning and I haven't gone to sleep yet.