TAM, I definitely understand your point of view (and no this is not meant to be another tongue in cheek Glock vs. 1911 tit-for-tat - being serious here). I felt that way for a long time and carried my Glock box stock for a decade.
But through my own experience and discussing triggers and safety etc with many many folks (including many wonderfully knowledgeable folks on this forum) I've come to the conclusion that keeping that booger hook off the bang switch is the A-number-1 most important safety feature of any gun. Everything else is just some degree of window dressing.
Certainly having an extra external manual safety (like a 1911 thumb safety) does help, but something you said above always gives me pause: This idea that a 1911 owner could accidentally hit the trigger and not have an ND because the manual thumb safety prevents it. I can't remember who first said this, but seems it is written in every gun manual I've ever read "Never rely on a mechanical safety"; put another way: follow the four rules - ALWAYS. I think I remember one of your posts a while back in which you'd carried one of your 1911s all day and realized upon taking it out of holster at end of day that at some point the mechanical safety had been switched off, unbeknownst to you.

What if you'd accidentally hit the trigger that day?
My point is, while external safeties and stiffer triggers can provide an extra level of safety, none of them will fully overcome the OOPS mistake of having your finger inside the trigger guard when it's not supposed to be. In some ways this all comes down to training, muscle memory, and even the user's own capacity for constant vigilance and adherence to the four rules.
In terms of a Glock trigger, I don't honestly think the difference between the stock trigger (about 5.5 lbs I believe) and the addition of the 3.5 connector (which actually only reduces trigger pull to 4.5 lbs) is going to make a huge difference in avoiding an ND. If your finger (or some other object like a retention strap) is inside the trigger guard when some amount of force is exerted on the gun, it's gonna go bang whether the trigger pull weight is 5.5 or 4.5 lbs. But a Glock can be set up to have a trigger as light as the lightest competition 1911 (without a thumb safety) or as heavy as a stock double-action revolver, and just about everything in between. The variance between a 2-lb hair trigger and a 10-lb NY-2 trigger IS more significant. On Glock race guns with true hair triggers down in the 2-lb range, I definitely see your argument and would never run such a trigger on a defensive gun. And I do believe that an 8-lb or 10-lb trigger like you get from the NY-1 and NY-2 trigger springs could help a bit avoiding ND problems, but those problems only occur in the first place if you've already broken the rules and placed a finger inside the trigger guard. And the heavier trigger greatly reduces my accuracy.
I don't run 8-lb or heavier triggers on my semi-auto guns because I have NEVER been able to adequately overcome the rapid degredation of my accuracy when pulling a heavy trigger (this is why personally I dislike DA/SA semi-autos like Sigs and older metal-frame S&Ws, though otherwise they are fantastic firearms). At the same time, I don't prefer to rely on a thumb safety like a 1911 (even though I love that gun design) because the only two NDs I've had in my entire life are from 1911-pattern guns. But also because every gun (striker-fired semi-autos and double-action revolvers) I own lacks a manual safety, and using such a gun for carry would require learning a new battery of arms, new muscle memory, etc. For this same reason - in opposite direction - I think it's great that S&W offers thumb safeties on the M&P series so that folks who're used to the 1911 battery of arms can feel comfortable sliding right into that weapon system.
As with most things outside the Four Rules (which should be chiseled in stone), I think a lot of this comes down to personal preference and the end user knowing his/her own tendencies and comfort level. If a thumb safety makes you feel safer, by all means buy guns with thumb safeties and use them. Me personally, I feel very safe with my slightly altered Glocks, which are always carried in holsters that fully cover the trigger guard and don't have extraneous retention devices that could lodge into the trigger guard. I prefer the simplicity of draw, acquire, fire (without that extra step of "drop safety") - just works best for me - and my triggers, while about a pound lighter than stock, just
feel better to me - my reason for using them has more to do with overall feel of the full trigger press/reset than merely pull weight.
As for legal consequences, I fully understand why many law enforcement agencies go with stock or heavier Glock triggers to try to reduce overall liability. Afterall they have dozens, hundreds, even thousands of officers of varying skill levels to worry about. I only have to worry about me. And for me personally, I don't really worry about legal consequences of a slightly modified trigger. I'm not a cop. I don't go chasing after bad guys, gun in hand etc. If I'm going to be hung out to dry for altering one part in a gun to make the trigger feel a bit better, which helps me shoot SAFER and MORE ACCURATELY then so be it. My goal is to never discharge my weapon at another human being. Ever. But if I ever have to discharge my weapon toward another human being, it will be to save a life - mine or someone elses. As long as I shoot accurately and only hit the bad guy, I'll fend off any other spurious claims as best I can. If I must shoot, I'd rather hit my target with a gun I'm comfortable shooting than miss with a trigger that is too heavy for my personal preference.
Anyway, I've spent WAY over my $0.02 allottment on this long-winded diatribe. TAM, as always no ill will intended at all - much respect for you
