It was the cast who felt cliche. You had the idiot heroine who was so very Mary-Sue (because EVERYONE loved her!!), the cool lesbian friend who hated men, the evil twin, a super-annoying "I'm so cutesy-wootsey" male crossdresser, the perverted doctor, the butler who does a face heel turn, the all-powerful amazing student council....just ugh. >_____> Like I said, we didn't hate it right away but when Haine's like "I'm not my father's real child so I need to bury myself in darkness again" we were like WHAT.....DA....F@CK....!?
It just stopped making sense. It felt like Arina herself was making it up as she went along.
I guess I haven't read enough shoujo like you have because I didn't think it was THAT cliche... Although I guess it's more cliche than all her other works (Except some of her one-shots but some are less cliche as well.)
Anyway I do know why Kyoko's ending was rushed it just sort of left a bad taste in my mouth
Spoiler for ending:
That they didn't do anything to help the dragon clan even though it was Hizuki's fault.
I used to like it a lot, heck I did a TON of fanart for it and even had a pathetic little website dedicated to it.
...........and then the plot went more and more downhill and everything became so stereotypical that I ended up hating it. >_< Not at first but after a second thorough reading and discussing it with my best friend (who used to love it as well) we concluded it's as cliche as cliche can get.
I'm not strongly attached to KYOKO but Arina has a good excuse for that one-she felt emotionally unwell and had to cancel the series so she wrapped it up really abruptly.