(The teal theme is purple, if you haven't tried that one)
You can change the colors of your page and your characters' pages with CSS. More themes is already on the site's to-do list, though :)
I can imagine that they're time-consuming to implement, so I can see that this wouldn't happen.
But I've gotta say, that while I myself really love the color pink, I would like to see some other colors other than two pink themes, three blue themes (including default), and a yellow.
Tried updating the colors of the buttons on my profile, and took me forever to realize why they weren't updating (because the buttons go on the color of the themes you use).
I don't know if you can see what themes others are using when you visit their profiles, or if their profiles change to your theme. But I'd like to see maybe purple themes, if possible?