I disagree with those who say the entire subject is obsolete due to the nature of modern jet operations (i.e. you won't have to "use" anything you learn in FPL) - the subject itself covers important concepts that remain valid even when you're not doing any hard calculations yourself.
Exactly. Look at the Westwind crew who didn't calculate accurate fuel, didn't calculate off track PNR when the weather deteriorated and ended up in the drink... some jet jobs don't give you a computer print out, and some in-flight fuel decisions aren't on any computer plan.