agree with a lot of these comments. I played up until about halfway through naxx, then onto TBC, then gave up a few months ago.
I remember sitting at my pc for hours upon hours as we wiped on Patchwerk, frittering away all the pots and flasks that I had spent copious amounts of time and gold accumulating. It just got so frustrating, just constant wipe wipe wipe all the time. And when we eventually beat a new boss, woo hoo one or two new items to share amongst 40 people.
That was even ok, but raiding in TBC just killed it off for me. Firstly the shift from 40 man to 10 and 25 man dungeons pretty much destroyed a lot of guilds. A lot of people ended up getting left out, and guilds that were big enough to have 2 raid groups ended up having arguments about which team was better and who deserved to be on it. It was a complete mess. Doing Kara was ok at first but then the old feelings of frustration came back - wipe after wipe after wipe for hours on end (bloody romeo and juliet), I just sat there thinking 'why am I wasting my time on this? I'm even enjoying it in any way...'
I stopped playing when my guild was working on Gruul, so not even seen any raid instances after that...BWL, that was a good example of a fun, well paced and balanced instance. Naxx was just too damn hard, it wasn't enjoyable.