Four reasons I can think.I do have to say though that I cannot for the life of me understand the hatred that there was for Kyle & Carol.
1. Ship one of them with someone else (I never favor two conflicting ships, although I know many people do)
2. Don't think their personalities suit
3. Find the history of women seemingly being passed around (by DC) between Lanterns to be annoying or creepy. It's happened several times.
4. An annoyance with Hal's supporting characters being parceled out to other Lanterns (instead of creating their own characters for them). This can be from fans of either Hal or other Lantern.