The idea of gaining experience from looting the dead is probably much simpler to implement for the devs. However, allowing for units, or individuals to acquire random items really adds the addictive, 'just one more go' gambling feel that the devs need to keep people playing/hooked.
If the loot was appropriate for the enemy, and somewhat random this is a winning combo. You could include potentially rare items but this would have to be controlled world wide to reduce inflation.
If you could allocate items to a unit, and randomly apply the visual effect to individuals within that unit that would be best imo. I feel that it's important to avoid having a block of soldiers that are walking in time with uniform weapon swings and identical armor, weapons, etc. Sure this would be appropriate for some units, (elite human cavalry?) but high inappropriate for orcs of any sort.
In short, people love to roll the dice... inlude as many forms of this in the game as you can and you'll have a winner.
Random is your friend.