Gulf War I was 25 years ago. To put that time shift in context, how many aircraft from 1966 were still considered vital combat assets in 1991? Also, what proportion of USMC missions were flown by AV-8B compared to CTOL USMC aircraft? I'd argue that the whole raison d'etre for Harrier died when the threat of the Soviet 3rd Shock Army rolling over the inner German border evaporated. I just don't see a case where we need rough-field STOVL operations today - it provides nothing that cannot be done with aircraft that can fly further and/or carry more.
Wouldn't that have been better performed by organically incorporating the Harrier into US Army forces Europe?