Why don't pick up trucks offer a (mild) hybrid system?

I admittedly don't know too much about trucks, so I'm making a few assumptions here - feel free to point out where I'm wrong.

Wouldn't a mild hybrid help out with a truck's function?

It would:

• Give a nice boost to torque, especially in the low end. Aren't trucks all about torque? Doesn't that help with towing, especially getting started?
• Improve MPG and emissions
• Lessen the dependency on bigger (less efficient) engines and lower turbo lag (instantaneous torque)

There's also loads of space for the hybrid components, given the huge engine bays and the ability to lay batteries flat in the truck bed?