The Kingdom, not Kingdom Come, and it was the moron Waid's idea.
Now why would you say Waid is a moron?
Kingdom Come was great. His run on Fantastic Four was propably the best in ages.
Hypertime may cause some headaches, but its how they fixed all the Hawkman problems of the past. And it really helps characterization, post-Crisis. Technically, there is no reason Green Arrow and Green Lantern should be friends. But via hypertime, the classic O'Neil/Adams run is still valid. They still went cross country together and Speedy still became a junkie.
In short, all hypertime does is allows writers to allude to old events in DC history. I really don't have a problem with that.