Penguin,
Stop trying to think you know something about this, you do not. Sending those troops back to the fight does not equate to a waste. Did you ever think that they would be able to lead and train their troops to be better soldiers and more effective war fighters? They now have experience that they can use to help their fellow soldiers fight smarter and better. Their leadership will help save more friendly troops and cause more enemy casualties by spreading the expertise around.
Yes they were given a very very high award. That does not mean they are now more valuable, they were just recognized for the actions they took on the battlefield. They were already valuable assets to the Corps before the award. Failing to use the combat expertise they have would be a huge loss to their fellow Marines.
Training stateside is one thing but their knowledge can be a big combat multiplier for the unit overseas where it has a bigger impact on the fighting.