Late, but I've never bought the conspiracy theory that the AH is linked to drop rates, either. The sheer number of checks the game would go through every time an item drops just seems like a monumental waste of overhead between the actual play server and the AH. "But it only checks on rare or higher!" There's still a check going on at the base level before even querying the AH were that the case. And then you have to somehow justify a stat weight where the game arbitrarily decides, "Well, we have 100 DEX/Crit%/CD%/ASPD gloves up, don't roll that!" I'd be far more inclined to believe Blizz would just buy these items from people with administrative accounts and deleting them from the game to preserve value. Of course, you can't really do that with the RMAH unless they selectively took a hit on those who opted for Blizz bucks.
No, drop rates sucked because you had numerous affixes for a given slot, and each time you rolled one you wanted, getting that second, third, fourth, and so on just becomes all that more computationally difficult. In FFXI terms, think of it like the reality of landing all 8 hits of Asuran Fists at capped ACC... but now x times worse. Tweaking drops to be class specific will help some here. Narrowing the affix roll range will also cut down on garbage rolls. You have no guarantee of a trifecta, of course, unless it's pre-built into something like a set/legendary. And honestly, we have no idea if the game weighted certain mods to roll more often, which can also suck up potential.
It's easy to say there's no proof Blizz isn't doing it, but there's also no proof they are. To me, they didn't need to. Loot conditions were winning lotto-like as is.