Do you mean the "view" in MVC or do you mean a grammatical syntactic restriction you're going to place upon yourself within the said 'view'.
Good point. Personally when I refer to template engine I refer to an system similar to Smarty.
My views are objects which use the template engine which then loads the template.
If you need your templates to have "steroids" I'd just extend the view, similar to how jquery extends javascript, it adds on to it's capabilities without destroying all design that the langauge designers put into the language for you, which is what smarty does.
My idea of a solid template engine is actually the opposite. using alternative syntax is powerful but perhaps a little to powerful. I am implementing a template engine to essentially prevent me from cheating or hacking and making template more prone to bad design.
For example, I have occassionally pulled on a model method inside a template or generated a list of items from a GLOBAL. I personally consider that a horrible practice, and I hate having that dependenciy in my template layer, so a template engine would prevent me from doing so, by offering a limited/subset version of the full imperative support provided by PHP.