I just finished Act 2 of hell last night, and a lot of what I see here doesn't jive.
First of all, since all of the gear you loot is for characters 5-10 levels behind you, the AH seems to be the only way to find gear with the full capabilities of what you're able to use for your CURRENT level. This is especially true for venturing into hell. I noticed this first with a Demon Hunter I had started and leveled to 15. I had saved some good rares from my WD play thru for this character, and the moment I was able to equip them, I saw a HUGE difference. I had previously noted some inability to loot a weapon, and that had held me back. I purchased a knife on the AH that upped me from a 82 dps to a 315 dps for minimal gold. I am just starting to loot weapons around the 300 dps mark, and at my next level up, I'll be switching to a 525 dps I got off the market for 5k. That's quite a difference. IMO, hell difficulty FORCES you to buy from the AH. I hadn't used it prior to reaching hell difficulty, so I don't see it as necessary to get that far, but to progress any further, you will have to. Those elites and champions are just too hard to damage without getting that damage # way up.
I can understand the complaints on the crafting, but remember that Blizzard doesn't set the market on the AH. The guy who sells his 500 dps WD knives for 5k does.
EDIT: Btw, because of all of this, I am currently running 51% Gold find, and that number will be closer to 70% when I level next.