Most Helpful Guy
Sometimes they are cute. Sometimes they aren't.
Sometimes they're perceived as childish for no other reason than they're short.
Most Helpful Girl
Because they are?
I don't like it if they 'act childish', but on their own, acting normally, they can be really cute. Petite is a cute word too. xD
And LovelySerene said it - it's the only thing they can pull off. They don't think they can be so sexy or 'hot' -- because they're little and, obviously, remind someone of children. O.o