> that severely limits who can be a soldier

But that's an economic problem, isn't it? Maybe if children stopped working, we couldn't make enough matches? But unless we recognise the morally undesirable, why would we care to change anything?

You can recognise something as morally undesirable, yet for some other reason unavoidable. There are many things that fall into that category.

It's also a slippery slope - if something is needed does that justify all means in getting it? And to what extent does America really need (a certain amount) of soldiers? It's one thing to defend its borders, but is every military action of necessity - as opposed to national will?