Why were soldiers allowed to bring items from the enemy home 40 years ago but suddenly can't today?

Answer 1

In previous eras, the military was willing to look the other way when it came to what could be taken back by soldiers. Today, the policy has changed somewhat, for two main reasons. First, anything that poses a potential health risk (weapons, ordinance, etc.) is strictly banned under the military's war trophy policy. Contrary to what the question implies, it IS still possible to take back many other kinds of items, so long as they are documented and approved by the chain of command.

Second, today's military is simply more sensitive to the issues of looting and theft that allowing war trophies creates. The military wants to create lasting peace in the regions in which it deploys, and allowing unrestricted war trophies is considered contrary to this goal. It might seem like harmless fun for soldiers to take items from the enemy as trophies, but the people in the nations who have their items taken often see it as theft, either personally (if it was their own item) or culturally (if it is an item of a relative or fellow countrymen).

Also, this change wasn't "sudden." This decision was made years ago, prior to Operation Iraqi Freedom. All soldiers should have been briefed on this policy, and given every opportunity to comply.