Depends, for instance the Zend framework - are you really going to use ALL of the available components? Probably not you'll use maybe the session, database, and one or two more components just detached those from the entire framework. As far jQuery you gotta decide on wether you need ALL that functionality if not I'd probably go with Rendair's Jooney (No offence, it's just smaller then jQuery), it has the AJAX and small cool effects. As far Smarty there are several alternative depending on what you really need.
But for a commercial product I would more then likely code everything myself that way I have a better mindset of how everything works as the bug reports come in (because they will no matter how much you test it) for a client website I'd use a framework simply because what if he wants something extra added and he can't hire you? The developer he hires most likely won't be to happy about having to learn a custom API
Keep in mind these frameworks are built with speed in mind as well as a heavy factor in how they write their code - if that ever changed not even the most loyal evangelist would stay with the framework.
"What everyone seems to forget is that while knowledge certainly is something - it's the implementation of knowledge that brings power" - Andres Galindo.