This question may be completly stupid, but it's still giving me a hard-time.
By looking at this demo :
I figured out that the Ascetica theme menu had some drop-down capabilities. Or I can't really figure out why it doesn't work. Unless the theme is somewhat altered on the wordpress.com version.
If someone had an idea about that?
Tried the dropdown menu i'm using on different other theme including Twenty Eleven. and it works just fine on there.