personal injury attorney here.
I can't really imagine dropping PIP coverage (it's technically allowed to be dropped in our state but NO ONE drops it)
Medical providers prefer PIP, because it generally pays better than health insurance, so the first benefit you have with PIP is that virtually anyone, from chiropractor to neurologist, will see you. Hell, I'm even convinced that some specialists move you up in the queue when you pay with PIP (just a theory, not confirmed).
Second, as has been mentioned, it acts as a first layer for medical bills. Your health insurance is fine as a second layer, but if you keep PIP, you can avoid the deductible as long as your total meds are until the PIP limit. This assumes you don't select a PIP deductible). Trust me, if you get hurt in an accident, it's reassuring to know there is extra protection.
Third, it also covers people riding in your vehicle. So that means your kiddos, spouse, even friends or extended family. So think of it as additional protection for people who might not have health insurance, or their own auto insurance.
Just some thoughts. I know it always comes down to money and assumption of risk.