You say you nerfed AK down to 40 levels to lower the amount of time people feel like they are horribly inefficient. Nicely thought out, but completly ineffectual. It's much easier to never give a kid candy then to give candy to the kid, make it wait for 2 months to get said candy, and then call backsies after a month. Regardless of if the kid ever deserved candy, that kid is going to be angry with you.
That's what you have done. Instead of feeling like their AP farming again means something at 40, you've essentially ensured that players will now feel that their AP farming is useless for the entire rest of the patch cycle. Congrats, you extended the problem you sought to fix indefinitely.