Not to pick a fight, because pragmatically I agree, but reservists take the same oath as active duty folks do--and that isn't to serve when there's an emergency. More money for soldiers is great; they work hard and put everything at risk. But we don't have a problem because of pay. We have a problem because the best of the military-age population has already volunteered, and many of the rest don't consider it duty or an honor to serve their nation's defense. The problem is cultural.
The problem with that philosophy is that it makes recruitment for the reserves darn near impossible. When people sign up for the reserves they're signing up to be part-timers. If we're going to frequently activate them and send them all over the globe then it's not a part time job anymore.