In short, I went from ecstatic to that sinking feeling you get when you realize that lovely Everglades condo is in fact just swamp. I'd just told everyone how awesome this change was, and here I stood on test with less AP than I had on live. Was it a huge loss? No, about 70 AP or so. But I still felt that lovely combination of chagrin and slight anger that comes from not only being wrong, but being wrong and finding yourself worse off than you'd been.
To be fair, the change to 20% has brought the AP back up to close to where it was. My warrior on test is lacking a couple of best in slot items that I've picked up since transfering him, which means that to compare them I have to take off bracers and neck and look at the AP from there, but we're talking a 20 AP drop now. The real issue is buffs like Blessing of Might/Battle Shout and procs like Berserking. On the other hand, Blessing of Kings, Gift of the Wild and Horn of Winter/Strenth of Earth just got better for us.
Now Ghostcrawler has waded into the fray, and what he says confirms it: this change is purely meant to force warriors away from wearing leather.