Being useless is part of he cuteness, I guess XD
It's the Japanese "hetare" concept XD

I'm probably not very amused by Shiki 'cause he looks like the classic "dark guy" type.
After the thousand series where you meet his type it becomes kinda boring XD --Another example of the character is Luka (http://cienviane.files.wordpress.com/2010/03/zesu.jpg) from Uraboku :3