Kes was the good girl, that was her casting. I never liked her at all, she pretty much embodies everything I dislike in certain female characters.
However since Voyager I have found characters who have the same soft way of talking and similar sweetness who I dislike FAR more, so Kes does not bother me as much.
One character with a similar way of being (all wise and quiet and gentle so I want to smack her) is Juliet on Lost. I HATED THAT CHARACTER SO MUCH. For the same reasons I initially hated Kes but at the end of the day Kes was an alien and therefore much more interesting and forgivable.