SethB:
As far as mass mobilization, I'm not very worried about having to do it. I think we will fight with what we have, and it will be small enough to not require mobilization, or it will be over before we could set up a draft anyway.
You may or may not be right. FWIW, roughly the same prediction was made by many in the 20s, the late 40s and again in the 50s and 70s. I don't think you are correct but what you or I think is immaterial, The Army and the Nation cannot afford to and will not operate on that premise. Like it or not, we're big and have to be prepared to be far bigger.

JMA:
I question this as if all you are looking for is someone to command a platoon most armies have an amazing number competent and experienced NCOs who can do that with ease.

This narrow view and concentration on the first step of the officer ladder may be one of the reasons why officer retention beyond subaltern is becoming a problem in many militaries. We may differ in this view.
No differing by me for one, I think you're spot on. The French, by tradition have two Lieutenants commanding Platoons and the other two are commanded by NCOs. Seems a sensible way to provide experience for a select few who are being groomed to do Officer stuff at echelons above company...

We say we're training future Commanders and Leaders and then we place most in an environment where they are charged with rote operations of questionable value while their drive and initiative gets trampled by set piece training and operations -- that drives many to depart after five years or so and the Army accepts that because a big war will see them called back.

The selection comments you made above are correct IMO. Pete is also mostly correct on why we do what we do. What we have done to pad the mobilization roster is to significantly 'over Officer' US Forces. We have a veritable horde of Generals; same rough number we had at the end of WW II and in the 80s with an almost 800K Army (and we were over officered than; we still have the same rough numbers with about 250-300k fewer troops). We're not approaching USSR norms yet but we do seem headed that way.

Those charged with selecting and training future Officers are generally doing the best they can with the hand they've been dealt and the products are generally really pretty good (there are always going to be a few less than stellar slip-throughs...) -- the real problem is that our Personnel system does not support the Army, it drives it...