Graystar,
Most combat guns with hammers are only 0% cocked. That's what a DA gun is. Anything you can do with a striker, you can do with a hammer. The USP LEM has a partially cocked mainspring, like the Glock. The Glock's not very compressed mainspring isn't unusual, especially if you consider it a type of DA. So does that mean that a Glock has only 30% of the safety feature a DA pistol has? (Obviously not.)
Your 4lbs. (or 2lbs.) 1911 trigger is guarded by a safety for holstering, running etc. I was really asking you how light a safetyless gun should be. So I'll ask again- how light is "safe" for a Glock trigger?
The HCI comment was just to underline that you were blaming a mechanical device for a human failure. "It wasn't the shooters fault, it was his trigger." Which is strange, because you're taking the opposite view when it comes to NDs.
As far as maximum DA pull weight, that can vary by design and shooter, but most literature seems to agree that a 12 lbs. DA pull is controllable enough. I would favor 10 lbs., which is enough resistance that the gun can still be stuck in a waistband or pocket, but is even smoother. A good Sig 22X trigger, or that of the Beretta 92D are good examples.
Obviously, there is a middle ground, and it's somewhere between 1 lbs. and 25 lbs. Up to 1985, it was somewhere between 9 lbs. and 15 lbs. Then all of a sudden 5 lbs. was acceptable. Everyone must have just gotten smarter and safer that year.
So, why not 15 lbs. triggers on all guns? Like I just outlined, there used to be a standard. Maybe not a fixed number, but not as light as Glock and its immitators. Personally, I think the public duped itself with talk of trigger safeties and the rules of gun handling into accepting something of marginal safety in favor of shooting ease, of all things. I think many PDs regret that decision. But there isn't an International pistol design safety council to advise or enforce, which is why anything goes.
Finally, I have no idea what kind of trigger your girlfriend's revolver had. But the pull weight itself is only one facet of trigger action. DA triggers don't have a definite let off point, Glocks do, which makes staging easy and accurate. In use, Glock is really a two stage SA trigger: you pull out the slack, then click through the sear release. Even with a heavy NY2 trigger, that's going to be an advantage over even a slightly lighter revolver trigger.