because they were too challenging

You don’t know that though. 6 bosses in Sunwell lasted us April until Wrath came out. We didn’t kill KJ before or wow 4.0 hit, unfortunately. Blizz released ALL of the TBC content within three months of that expansion being released, and with that came a 13 month dry spell of nothing new besides a 10 man for the people who couldn’t defeat SSC, TK, et al. because they were too challenging.

Reducing heroic encounters to "the same boss with 1-2 new abilities" is kind of silly in my opinion. In my opinion, the heroic encounters are far more fun than their normal counterparts; moreover, they are a true test of your raids abilities and separate the men from the boys and the women from the girls.