Cata was also the epitome of intrusive botting. I mean forget farming mats for anything... at any given time there were at least a dozen bots farming ores/herbs in deepholm and ulduum. This meant if you wanted flasks/crafting mats you had to buy them off the AH from all the bots. This totally fucked the economy. And since the botting went on for so long with Blizz doing nothing about it, a lot of people ended up botting (if you can't beat 'em, join 'em)... then they all got banned in a big wave. Of the top 4 guilds on my server at the time, all of them lost at least a quarter of the players. Most of the rest of us just didn't have the energy to re-recruit them and just quit the game.

When I came back after a year-long break, LFR had already taken its toll on the player population. Item level had become institutionalized. The average player was considerably worse at the game. All the sandbox elements that used to make the game fun (world pvp, server community sponsored events like hide-and-go-seek, lvl 1 races, kiting that CoT dragon to Org, For the Horde/for the alliance raids/defenses) were completely gone. You did you fire lands dailies, you raided, you logged off. Boring as fuck. So I quit again.

I came back during the end of MoP... the game was in kind of an ok state. Rather than dailies, you killed shit on timeless isle. At least there was a little bit of spontaneity. But the average player ability was noticeably even worse than during cata. Players were being spoiled by LFR, so they were content sucking. It used to be that if you wanted gear, you minimally had to be good enough for a guild to take you or rich enough to buy a run, now you could get carried through LFR and stuff like OQ once you had a high enough ilvl.

So why was Cata so bad? Well it marked the turning point when there was a significant change in the leadership of the dev team and the game started changing into the stupidity (it's basically an expensive skin for facebook games) that it is today.