There are different concepts of what a soldier ought to be.

For large swathes of history, a 'soldier' was essentially meant to be a slave. Often they were taken straight from the dungeons (or the gallows), or the poorhouses, or pressed into service from a captured ship, or whatever other shit situation, and the contract entered was 'you will do whatever we say and we'll feed you and clothe you until those orders result in your death -- or we could just kill you now.' 

These soldiers performed adequately. They reflected a commander's competency, because they were neither encouraged nor ALLOWED to deviate from that commander's orders. So as long as you had a good general who maintained proper discipline, your army was set. 

What we've realized -- and why we've moved away from the draft -- is that there's a better soldier out there -- the one who is highly trained and exceedingly competent, and capable of forming and acting upon his own initiative. Ten of these soldiers can do the work of hundreds of drones -- and yes, they have more technology, but so do the enemies, and besides this is a soldier you can *trust* with an Abrams tank, and if an opportunity arises in which that asset can give an advantage, the soldier is prepared to act.

Now to maintain order in an army of drones, you have to occasionally flog the malcontents and keelhaul a few traitors. British sergeants used to march behind their units with a pike to remind everyone that if they disobeyed or fled, he could cut them down. Russians mounted machine guns behind their advancing lines and opened fire if the conscripts retreated. These were necessary precautions, but inefficient -- you wasted all that food and supply on soldiers you wound up killing later, and your best, most trustworthy men aren't out there fighting -- they're holding the pike, or manning the machine gun aimed at your own soldiers. Huge waste of money and talent. Our modern soldiers not only perform better on the field, they do so without the inefficiency. And the only price is, you must command them in such a way that does not assault their sense of honor. If you do that, your proud soldiers will fight harder, better, and cheaper.

Without even [b]approaching[/b] the moral argument, it all makes sense, right? Now throw in the moral high ground, and the strategic advantages gained from the moral high ground. It's no contest.