Kyle's only come into his own for me relatively recently (well, in the last several years or so). The biggest problem, really, is that he came on the heels of a pretty popular Green Lantern run, and a storyline which long-time GL fans felt was way out of character for Hal - to go basically bugfuck and try and rewrite the universe. How out of character was this? Well, consider Geoff Johns had to explain that he was being possessed at the time.
So you've got a newbie replacing an already beloved character who went out in an unpopular way. Which is not to say that it could not be done (case in point, Jaime Reyes), but instead of trying to show Kyle growing into the role, DC kept telling us how gosh-darn great Kyle was and how he was so much better than Hal, instead of at least paying respect to his predecessor (to be fair, this was tough, since they had made him a villain) or letting us see and relate to him. Flame wars over Hal vs. Kyle also didn't help.
Not saying who was right or wrong, just that Kyle's introduction was badly handled. In contrast, look at how Jaime's inheritance of the Blue Beetle mantle was done.