Smarty templating is optional but easy to set up. Smarty seems to be a religious topic for PHP developers. Switching between Native views and Smarty views for a controller is done in a single annotation on a per controller basis.

Why does everybody hate Smarty? Explain please.

The trade off between wasted processing and elegance is not high enough for most people. I could see it being nice if you are giving access to "non-developers" to modify the views/templates of your system and want to make sure they only have access to a given subset of functionality.

Smarty compiles its templates, so only the first execution takes the processing hit. If you have APC, the hit is also very small.

Smarty is simply obfusication. As the other reply suggests it adds no ease for non programmers to make changes. It doesn't add human readability.

Ultimatley PHP short syntax is just simpler (especially if your using an MVC framework or similar).

You're ignoring quite a few features of Smarty, and I disagree with you on human readability.

The other reply also wasn't saying anything about ease. It was about control, which is also important once your team reaches a certain size/level of skill diversity.