How to fix it?
Well, AQW was not always boring and uninteresting to me. I can recall some of my favorite moment, like Bloodtusk Saga, Desoloth, Final Chaos Lord, and so on.
I don't know how to fix it, but I can think where to start. Start with looking back. Look for everything back.
I know that most of the issue (unbalanced classes, boring story, money grinding, RNG) could be fixed if they compare them to the past release.
So they would do the right things in the past again and could learn their mistake (intentionally or not).
For instance, I know many people don't like Naval Commander (same design over and over; don't forget about its crooked neck) but they kept doing it. Why? Because they listen people ONLY with good sentiment about them. I can see from Twitter. The same thing happen to Starsword, Upholder, Monglowen, and other "boring but repeated" things/events.