Rule #3 is VERY important with a Glock, moreso than any other make.
Personally, I consider anything less than 8lbs to be a single-action trigger, and I'd be kind of antsy without a safety. Overkill? Probably. I (as in, ME, not everyone else) just have this <8lbs-needs to be decocked, >8lbs-safe mentality when I holster a gun.
Is the Glock inherently unsafe? Not in the right hands. Problem is, LOTS of new shooters with little or no training are buying these things like crazy, and I've seen more than a few NDs, including two that weren't at a range. What's more is, under extreme stress, I'm not sure lots of folks will have anything but the muddiest sense of trigger discipline.
Glocks are a neat design, and I may break into peer-pressure and get one someday, but when I see a newbie with one, I usually keep my distance.