*ahem* Naeomie's point, if I understood it, was that between levels 15 and 20, the players you encounter have never been in dungeons before and don't know what they are doing, and due to the accelerated XP gain, they level beyond 20 well before they've really learned much about dungeoning and understanding that a healer can do more than just heal. Unless you're lucky enough to get someone in your group who is an experienced player levelling through a new character, you're basically either grouping with fellow F2P seasoned people, or you're playing with fresh newbies.
In my opinion, if you want to make lemonade out of your lemons, use it as an opportunity to demonstrate and teach new people what is possible. Rather than make it about you ("I DPS and tank because I can"), make it about the class (Paladins are a hybrid class capable of filling multiple roles, and in this way I'm helping the group get through the dungeon faster").
Hope that clears up a few things.