How successful was the Harrier?

Whilst the Harrier has served with distinction with the RAF, RN, USMC, India, Spain, Italy & Thailand, it still seems a modest career compared to the great things predicted for it in the 60’s & 70’s. It was claimed then that long paved runways were so vulnerable to IRBM attack that the only way forward was VTOL or STOVL and that the Harrier and it’s ilk would be needed in their thousands. And yet with the possible exception of the Gulf Wars, have IRBM’s ever really been used to attack airfields? One final question, how close did we get to selling it to China, and was the deal really scuppered by the US?