Nothing wrong with conventional earplugs, they fulfill their purpose. The reason the QuietPro is superior is that it enhances hearing for lower noise levels, while blocking damaging noise levels. In other words you won't miss an order, and you won't risk your hearing either.
Anything that enhances a soldier's performance in both the short and long-term, while reducing the risks they have to face, is a good fit in my books.
I believe newer models function as communications devices as well, serving a dual purpose. They are worth a look, here's the developers website: http://www.nacre.no/