@alacaelum
@Leemac13
I'm not Japanese so I can't say 100% that I understand their view on this, but I always though that many authors go with Loli vampires because:
A ) Japanese like their lolis, of course.
Or
B ) Vampires represent Inmortality and Eternal Youth, and nothing says "Youth" more than teenagers and kids.
Or
C ) By lore many vampires are ancient beings that had lived for centuries or even millennia, and in many series they where transformed into vampires by some kind of partner in something similar to a marriage ritual. Marriage age in those times was lower than in modern times, so in a way it makes sense that there are so many young looking vampires.