Of Jeff Cooper's now universal Four Rules for Safe Gunhandling, it seems to me that the person shown in Post 1 violated numbers 1, 2, 3 and 4.
I do not believe the Glock has a "design flaw" as a result of having to dry fire the unloaded weapon to allow the slide assembly to pass over the cruciform in order to separate the upper from the lower.
Designing around the inattentive user always presents serious challenges, and it seems that an inattentive person will always figure out a way to blast themselves provided they have a working weapon.
Disassembly of a Glock is completely safe provided you UNLOAD it before beginning the process.
Additional safety measures which should be observed when disassembling the Glock would include not putting any part of your body in front of the muzzle, pointing the muzzle in a safe direction, making sure you know that no part of your body is the "backstop" in case you negligently fire the weapon during the process, and making sure your finger isn't on the trigger until you are ready to properly "dry fire" for disassembly purposes.
Each one of these are fully applicable to disassembly of any weapon, not just a Glock.
If one cannot operate equipment safely and correctly, one should not be allowed equipment.
Other safety features that are debatable on firearms are things such as magazine safeties, which are nearly always thought of as a bad idea for various reasons, even though there seem to be a great many people who cannot remember that removing the magazine ALWAYS comes before clearing the chamber. Even a safety lever, which decades ago was a mainstay in self-loader design, is now out of favor except for the 1911 and the P35. Beginning with the West German Police pistol trials in the 1970s, it has now become almost universal doctrine that there should be no safety lever which someone might forget to deactivate in a time of need. Of course, what they meant to say was, "we hire a bunch of people who know not the first thing about guns and we need a really simple mechanism because Europeans have no experience with guns of any kind before they come to our inadequate training program, and besides that, we don't teach much about guns because even our instructors don't know that much, because guns are only grudgingly allowed and we discourage their use in any circumstance because we are really all anti-gun."
In any event, it seems that America is, not surprisingly, still a mere 40 or so years behind the "socialist state of Europe" - I mean the European Union.
The real problem is consumer protection laws. The poor guy pictured in Post 1 would not even be here if there were no such laws as his "line" would have died out by now left to their own devices, as someone in his genetic tree would have bled to death from sticking their fingers into a fan, or been electrocuted changing the bulb in the fixture above the tub while taking a bath or by some other means.
The results of making machines "idiot proof" is the proliferation of idiots.
Sorry. Couldn't resist.