I'm no military expert but even I know that things have changed since Vietnam. Smart bombs and guided missiles mean that a single aircraft can take out bunkers and gun emplacements with more accuracy that a World War II era cannon. A carrier airplane can bomb targets on the beach and for hundreds of miles inshore. In the mean time the Marines have not landed on a defended beach in almost 70 years. Spending millions to keep a ship around on the off chance it might prove useful makes no sense to me.
Saddam was stupid, he should have never stopped when he invaded Kuwait. There was nothing stopping him from taking the entire Saudi Peninsula. If he had done that then a hostile shore invasion was going to be necessary to reclaim that real estate.
We haven't used Nuclear Weapons in 67 years and they are still kept around.
And why M-16 still come with a Bayonet Mount.
It has been estimated that their were no more than 15,000 insurgents in Iraq armed with Dumb Mortars and 50 Cal on a pick-up truck and look what they did. When your advanced and expensive toys fail you, you always need tried and true methods.
The Air Force said going into Vietnam "We will never fight another conventional war again" and sank all their resources into Nuke Capable Bombers, Fighters and Missiles.
All the wrong tools to fight that war and we are repeating the exact same mistake today.