cata was shit. here's a list why.
1. blizz put too much development time into the 1-60 rehash, 80-85 was ok, but once you were level capped, there was very little to do
2. archaeology was a huge time sink
3. the 5 mans were horrendous, too few in number and overtuned for pugs (organised groups did fine though)
4. we were promised more raid content than ever before, yet got less
5. they cancelled war of the ancients the raid, then made it into a sucky 5 man.
6. they cancelled the abyssal maw raid and gave us no ending to the neptulon story
7. they nerfed the shit out of every raid by 30% as soon as the next tier came out and funneled everybody into the next tier, regardless of their progress.
8. catch up dungeons exacerbated point 7.
9. the deathwing raid was woefully dissapointing and lasted far too long as they had a lot of development to catch up on after the 1-60 rehash.
i think thats enough for now.
my guild went from a strong, regular attendance raiding guild, to an empty husk of a guild over the course of cata - outside of raiding, everybody got bored shitless, to the point where we all gave swtor a try for a couple of months because we were all so bored of cata.
anyone who had already levelled a few toons to 80 before cata, all of a sudden had very little to do other than raid or level alts. outside of raid days, you started to see less and less people log on as they'd finish levelling their alts then logoff til raid day again, it was thoroughly depressing. i ended up taking a 6 month break and came back about a month before MoP when all the new talents were put in.