I'm a bit late to the party but I kind of want to bring up a few issues too. I'm going to mostly ignore the usual points that a person playing a different way shouldn't be punished as it doesn't impact anyone elses fun. I will accept the idea that the servers were unstable from AE, I can see that being plausible. The problem though is that AE has a lot of other good uses, and it feels less like the changes being made are to keep the servers stable and are more there to, well, punish AE users or try to make it so that no one wants to use it.
The thing is AE is actually pretty good as a stopgap tool, it allows people with alts (and let's be honest here, this game will make you an altaholic, the most powerful endboss is in fact the character creator) to level without having to go through the same missions ad infinitum. It can also allow someone to get some extra resources to say help their superteam build a base or finish off a set they were working on.
Now, if the XP gains are somehow overly..generous, well why not just adjust game XP. Look I'll be honest the 150%-200% XP going on feels pretty nice and the growth rate isn't bad, especially when we want to retain players and there is a lot of reason to make new characters. I also want to point out that the XP nerfs may exacerbate the farmer problem. To put it a bit differently, if I get sick of the usual missions I could look for some stuff that looks fun in AE, but the XP nerfs suddenly make that less viable. If I want to be able to level and not ahve to redo the same missions, farming maps become the main viable alternative.
Also it does feel like the general loot is getting nerfed too. As someone who would rather not have to spend half their free time at the auction house being able to farm up loot is rather preferable in these situations. But then maybe I'm wrong and others know something I don't, but the fact is that right now it feels like people that want to use this, whether to farm or to tell their own stories and explore options, are being punished and that seems...well not so good to put it mildly