The reason is that the bass only goes to about 33hz. therefore not overpowering the smaller rooms. At RMAF, the 9900 K2's in the trailer sounded MUCH better than the Everests in the main building. In fact, I almost bought the 9900's, which have yet to make it to the JBL website, for some reason.
I've noticed on Agon that some people are pretty "proud" of their 20 yr-old JBLs trying to get 3 and 4 times what they originally cost- they have remained unsold for quite a while now. Guess they really don't want to sell them....