In a submission from ek, there's a pointer to a new piece on php.ryannorris.com about Tiered Application Development in PHP.

Confused? Well, "tiered development" has a pretty simple definition - tiered logic separates out the different "layers" of your application, making them all abstract and easy to move around. In this article, they talk about this method of formatting your code, including all of the benefits surrounding it. Creating code with this idea in mind can not only made things simpler down the road, but can also make it easier to have "middle tier developers" creating the parts in between.

So in the final analysis, it's obvious that this (very rudimentary) multi-tiered architecture that I've demonstrated does two things - abstracts the presentation logic and the business logic into separate compartments, and adds several additional SLOC. I've run into my fair share of PHP developers that take issue with this, saying it complicates their lives more than it simplifies them by having to manage more code in different locations. The other popular argument against Template packages in particular is that it usually adds Yet Another Language, and most engineers will agree that they usually don't have enough time to get involved in such things...