Nah, Reise, I actually agree with you. Running with a pistol cocked and hot isn't wise, even in a combat zone (certain rifles are another story, though.)
I hadn't noticed the Luger stuff... I usually use the P38.
Research time, to see if this makes sense or not...
Decocking the TT33 WAS the safety, I just looked it up, it used a half-cock position (though any imports to the US had an external safety installed per BATF regulations.) It's also SA-only... Answers that.
The P38 apparently was not only DA/SA, but had/has an external safety on the left side and what looks like a decocking mechanism on the slide. I will point out, though that I don't know if I would trust a decocking mechanism (I've heard of them failing and causing negligent discharges) and that running around with the hammer cocked on any pistol, safety on or not (I do know I never trust a safety) isn't the greatest idea in the world.
Oh, and firing a DA/SA weapon in DA mode? I have one word for it: sucks. Cocking the hammer on a pistol is so easy to incorporate into raising it that it doesn't really add any extra time.
The Luger... is hammerless so it can't be decocked (way ahead of it's time. Welcome back to the age of Double-Action Only pistols.

), and has an external safety located on the left rear of the pistol. Maybe they're engaging the safety where you can't see? Dunno.
As far as USING the pistols (since this IS tactics and all...) I prefer to aim center mass and give about three rounds rapidly. That usually puts them down for the count.