The problem with Kyle was that he had no connection to the Green Lantern mythos.
Hal Jordan never had a kid sidekick like the Flash, and so there was no logical successor to Jordan other than John Stewart. I have always been scathing of DC's decision not to entrust the most powerful weapon in the universe to a black man - it was a commercial cop out because sales of comics with black characters traditionally don't do too well (explicitly recognised by Christopher Priest in the foreward to the first Black Panther tpb).
Kyle was an anonymous white guy who got the ring, and people hated his anonymity. If they wanted to maintain some sort of continuity legacy, and they should have to appease fans, why not give it to an established hero like Adam Strange, the Creeper, or Captain Comet, or do the Witchblade cheesecake thing with Starfire.
Having said that, I did very much like the depiction of GL in Morrison's JLA: Earth 2 (which is the only time I've read a story with the character in it), because Kyle did come across as quite different from the rest of the characters - he was trying his best, as opposed to supremely confident.
