I always have to wonder why her and many other cosplayers can't seem to stick their tongue out past their lips. >_>

They'll make their lipstick smear or something in that area.

They're trying to be cute, by making the action small.

I think it looks funny... like they have burger lips.

Afraid of smearing lipstick with their tonuge? aaa no. imo
That action alone will not smear lipstick.