It is limited to the tools and documentation they give you.

For me, Theme Builder is limited. The templates I'm provided with and according to the documentation they are the only ones available to me and anyone else who downloads it. Just because you have found a way to edit other templates in there doesn't all of a sudden say Theme Builder has so much more functionality. It says you found a way to edit the T-mobile theme with Theme Builder and you don't want to tell anyone.

I don't think anyone here would argue that if more templates were available theme builder would be able to use them. Also, most times I've complained about Theme Builder's limited functionality it has come in the way of things you can't do with it... such as I can't move the applications screen up 25 pixels as needed, i can't change the font for incoming calls. These are not options provided by theme builder. If you know another way to do it outside of the theme builder that's super but it doesn't make the actual program any more useful.