It is true that Kairi was a great person. She was smart, funny, and cool. However, many of the staff members felt that Kairi was staring to let her emotions take over her admin responsibilities. I won't name their names, but they know who they are.
In my opinion, PC still is in good hands. Andy and Jake are two very capable members, and some of the admins are becoming moreand more active. Kairi demoting herself isn't the end of PC as we know it, she will still post about as a regular member, so will a1337a.