If you "wrap" an HTML::Template object in your own object you need to expose all the functionality in HTML::Template that you use by providing wrapper methods in your class. Where you provide some added value that is fine, but if all you are doing is passing a bunch of parameters through to the underlying object then you are simply buying extra work for yourself.

On the other hand if you derive from HTML::Template you only need provide the added value methods. Everything else is served out of the base class.