1 The people making policies like this think EVERYBODY is a loose cannon. Soldiers, police, average citizens. They're reasoning by analogy: They know they're sociopaths who'd as soon kill the people they see around them as say hello, they assume everybody else is as crazy.
They don't trust the police, they don't trust the military, but can't get by without them. So they only arm them when they can't avoid it.

2

...we've already crossed the "blatantly obvious" threshold...

Unless you are CNN, in which case, you are unwilling to infer that the shooter was Muslim based on his name (Which...Might actually make sense IF that was only thing CNN went off the rails on.), as well as saying that shopping malls 'were places you wouldn't anticipate attacks.'  No doubt the victims of Westgate would dispute that assertion.

3 To be fair, having soldiers generally disarmed except those on specific duty is hardly new.

Originally it turned on discipline issues. If you issue soldiers guns and ammunition when they don't need it, a percentage of those will go missing as they're lost, stolen, or (most likely) sold. You can easily end up with a unit with 200 men and fifty rifles when the penny drops.

And, not to put too fine a point on it, soldiers are not exactly selected for their retiring, reticent natures - making sure they weren't running around strapped has probably saved quite a few lives over the years.

Of course, what makes sense in the context of an ostensibly-secure military base makes a lot less sense in a shopping mall outlet with a couple desks inside. But I can definitely see the military making that call - culturally, they are comfortable with the idea that soldiers who are not carrying arms as party of their duty at the moment will not be armed.

4 It's unfortunately a rather simple calculation of career risk on the part of commanding officers.  Post WWII we kept our officer corps big so we wouldn't have a repeat of the WWII buildup nightmare, so there's an up or out policy, and perfect Officer Efficiency Reports are a necessity of staying in the game and getting promoted instead of being shown the door, perhaps before they can put in the 20 years required for a pension.  None could get away with Patton's interwar "This officer would be invaluable in time of war but is a disturbing element in time of peace."
 
If their unit is attacked, their career will most likely be over.  If one of the men under their command has a negligent discharge, their career will be over.  The odds of the former are so much smaller than the latter that we end up with travesties where sentries are not allowed to even have magazines inserted in their rifles, they've got to keep them in their pockets, sometimes even with a strip of tape on top.  This killed 307 in the Beirut barracks bombing, and was widely reported to still be the general policy after 9/11.

So if sentries aren't allowed to be effectively armed, are essentially disposable tripwires, the chances that those inside a base or facility will be allowed to arm themselves is nil.  And that's before we get into the anti-gun ethos which a lot of those in the military who are not on the sharp end of the spear buy into.  Or look at the bottom line of our men being armed with a known ineffective poodle shooter since the late '70s (M16/M4); the people in charge just don't care.

Side note: based on early reports, it looks like he started his shooting spree at another Gun Free Zone, and the police were already in pursuit when he shot up the recruiting center; like at Ford Hood, the police can avenge you, but can't initially protect you.

5 Hga's report is all sorts of horrifying. In the USSR, it was the SOP to keep guns and ammo under a lock and key, in case. Heck the commandant's patrol was armed with detached bayonets in town. Because who knows, what if a soldier flips out and decides to assasinate a Party official? And yet sentry was always armed.

6

There are some differences: The Red Army's recruits were and still are all drafted, involuntary. And a lot of them (probably about half) came from occupied territories where anti-USSR sentiment ran high (such as Chechnya).

The US Army has been all-volunteer since the 1970's. Morale in the US Army is a lot different than in the Red Army. Our soldiers are there because they want to be, and because they believe in the mission.

The Red Army also didn't train their soldiers (because it cost too much) but our soldiers get a lot of training. See this for more.

Frankly, if I was an officer in the Red Army I wouldn't want my enlisted to be carrying live weapons around me, either. But the US Army isn't the same, and I trust those men completely.

7 <i>Frankly, if I was an officer in the Red Army I wouldn't want my enlisted to be carrying live weapons around me, either. But the US Army isn't the same, and I trust those men completely.</i>

*You* trust those men completely. Our political class (including a disturbing proportion of the officer corps) sees those men as unpredictable members of an enemy tribe who serve under them for reasons they cannot quite understand. It's more or less *exactly* the same motive as that of the people in charge of the red army disarming their men: They are afraid of them and what they might do.

I was once in the Air Force for a while, and aside from the ten rounds we fired at field training, we received *no* serious real training in how to handle weapons, nor were we allowed to do so on or near base. (Granted, I was nowhere near the "pointy end" of anything, but still...) I've done more pistol shooting in my free time than I ever did as part of a military organization.

8 In order to meet our weapons training requirement (bureaucracy A checks the box of bureaucracy B, and nothing physical is done), our directorate gave us powerpoint presentations on how to maintain/clean the M-4. I kid you not: a web powerpoint presentation was our weapons training for several years.

Actually, there is a lot about the way the base I was stationed at functioned that disturbed me. One of the things that got to me after a while was the sheer ineffectualness of everything: Nothing worked! Nothing! The security was a sham.  The base motorpool didn't actually maintain our dilapidated fleet of rusting to pieces trucks: They filled out paperwork and made sure all the papers were in order, but they wouldn't repair anything. They contracted that out occasionally when it absolutely had to be done, but it wasn't coming out of their budget. (Stories there too of figuring out what to do with a truck with half a brake disc in the middle of nowhere desert southwest...)

The ten thousand odd people busily spent their day turning the crank on a bureaucracy that *did* nothing physical. Whenever something actually needed to happen in the actual real world, it was contracted to private civilian contractors.