I've been away for about a year and I decided to clear up some extra schedule to take advantage of the AH before it closes permanently, but in my fiddling I was introduced to the new Monster Power (MP) system. I am a Lvl 60 Paragon 6 wiz w/ some seriously powerful items including 4/5 Tal Rasha's set and Chantodo's Will/Force (you can check my profile, it's all pretty much the most hyped wiz gear online and a lot of them are high level bonuses), but when I turn on MP 9, I get my butt royally handed to me on a platter. At MP 7, it takes some serious strategy and potion-management to survive, and I'm using Archon about as often as possible. At MP 4, I can win every battle, but not without thinking. If I lose focus or get cocky, I'm dead. This is awesome to me, because I was getting a little tired of blizzard, disintegrate, electrocute to charge, repeat (and keeping my shield up) just killing every thing with no thought at all, even Diablo. MP 4 is a lot of fun for me and involves some pretty intense strategy, MP 7 even more so, even with my totally epic set gear, so I don't understand why we need to get rid of the AH when players have other new ways to challenge themselves.
Judging by my recent (and comparatively limited) experience, you'd have to be Paragon 90+ after the Paragon stat system launches to really do well in MP 10 - with totally decked out gear. The AH is what makes this possible. As with the last 2 Diablo games, I really doubt I'm ever going to find all of Tal Rasha's set, Chantodo's, Vile Ward, Blackthorne's, etc., with one account, and if I could, then the game would be obviously rigged and way less fun than with the AH. At least with the AH you're making a sacrifice (money or gold) to get the gear you really want, and possibly planning a strategic budget / "business plan" (for killing digital demons). I never once in LoD found a whole set on my own; I had to find players to trade with and pay/trade them (sometimes resorting to purchasing gold illegally).
With the AH gone, we will see a lot more illegal gold farmers and a lot more chat spammers - is this really what we want? If for all of my future characters I will have to deal with shady characters to even have a chance at getting the gear I want, or if it was just handed to me, I would have a lot less fun. The AH is extremely fun for me, possibly my favorite part of the game, and I spend a lot of my play time browsing. I like trade aspects of MMOs, and I love the fact that I finally can be the character I want to be, which I never could in previous games. If this was real life and I was out killing demons with lasers and collecting gold all day, of course I would be spending said gold in the market on epic gear. In any of my passions or hobbies, when I make some extra money with it I invest back into the hobby. It makes sense... And IRL I can just get on eBay and have anything I could ever want, as long as I've got the cash, whether I built a company from scratch, got the money from my parents, or stole it off a dead body.
The AH makes the game more immersing and realistic, and I feel like the people complaining about it are somewhat jealous and/or would spend way too much money irresponsibly in the AH if they had it. So why is this no big deal for the WoW cash CoW? People take advantage of that game every day, even spending $5,000+ on a character that already AH'd tons of epic gear. There's nothing wrong with that - if you have $5,000 to blow on looking really cool in a video game, you obviously need that self-esteem boost and probably spend a lot more money on less effective means of entertainment elsewhere. These nuts will find a way to buy what they want, they always do. At least Blizzard gets a cut when you can buy the money straight from them.