Neither Kael and Vashj are hard - they both just have a lot of intricasies (sp) that, if one, two or three people screw up on, can cause a wipe.

There's two reasons why people hate attuning new members to Hyjal - firstly, they're both very long fights. Both of the fights are over 10 minutes long, and that's if you were to one shot. It can get very annoying.

The main reason though is that, not only do you have to do it for everyone, but you have to clear the entire instance first. It's not as big an issue in TK as it can easily be cleared in a night. But SSC, while being clearable in one night, involves 5 bosses. If your raid were to be off it's game, you'd be stuck in the place for 2 nights.

So, 2-3 nights in T5 content when your guild has killed the 2 bosses blocking entry to Hyjal. Yep, very annoying. While I think they should have just reinstated the scrolls Vashj and Kael used to carry, but change them to create a vial in 5 people's inventories', anything allowing people to more easy access T6 is a godsend in my book.