Condition 2 has a round in the chamber, the hammer down, and a loaded mag. I'm guessing you're thinking of Condition 3, which has an empty chamber, the hammer down, and a loaded mag.
As for military units carrying Condition 3 firearms, that's not because it's ever considered to be a more effective way of carrying a gun; some military unit commanders specify Condition 3 simply because they don't trust their troops with a round in the chamber. And often the primary justification many people give for not having a round in the chamber is because "the Israelis do it".
But "Israeli carry" isn't ubiquitous across all Israeli military units, it was simply a method that was once devised to adapt handgun training to every possible handgun that might be encountered. The idea was that some older handguns aren't safe to carry with a round in the chamber, and therefore the method of carrying in Condition 3 worked for every semi-auto handgun out there.
But most of us don't have to worry about carrying older handguns that aren't safe to carry in Condition 1 (cocked with a round in the chamber). Also, as civilians we can't just pull our guns when we think we might need them, we have to wait until it's actually justified. That means we may end up drawing our guns right before we need them, and at that point needing to rack the slide adds in a a crucial extra step on order to put the gun into action.
In my opinion, a civilian carrying a handgun in Condition 3 is a very bad idea. To me, it's less about the extra time it takes to rack the slide, and more about the fact I need two hands to do it. What if my off-hand is opening a door, carrying a bag, holding my child, or fighting off an attacker who got too close? At that point a carry gun in Condition 3 might as well be in Condition 4 (completely empty).
How many elite military units currently train their members to carry a handgun without a round in the chamber? I'd be willing to bet that number is zero.
