You are very naive in your thinking about templates. Yes, they do have a very basic function in common, which is to take a layout and a set of variables and produce something with those two things. However, templating is a much more complex task than communicating with a database (which isn't trivial).

I wrote and maintain PDF::Template, Excel::Template, and Graph::Template. They're designed to work with HTML::Template. When I started looking at TT, I wanted to reuse those modules. Then, I realized that what I was trying to do was hopeless. The data structures used are so different and the expectations of the client are different.

Now, TT may be what you're looking to use. It is an attempt to make using templates very generic and extensible. H::T was written a long time before Template Toolkit. (Correct me if I'm wrong, but wasn't TT a response to H::T's deliberate lack of features?) Just because it isn't the DBI of templates doesn't mean it doesn't do what you need. And, there's a book on it, too! :-)