As a former US Marine, I find myself in agreement with Brick and Orac as to the relative success, or a better term, popularity of the Harrier.
The Marine Corps fancies itself expeditionary. That's an Indian term for get there with not nearly enough airpower to sustain anything but a minimal threat unless deployed at MEF level. As such there is a view that aircraft are disposable in a way that the other services don't share. When you look over your shoulder and hope to see your organic heavy weapons in support and it dawns on you that the MPS ships are still two days sail away, you know that at least your gonna have a handful of Harriers no more than a few dozen miles away.