Please allow me to chip in with a few thoughts of mine.
As you pointed out, the Airbus family have pretty good and safe planes with lots of 'self-protection'. Saying a drunk pilot can pilot it is however a gross overstatement. I get it you do not mean it literally but only figuratively but even then, human errors have no bound and its hard to build a fool-proof machine.
We do not know what exactly happened and I am not trying to plane the pilot, but we must realize that human factors are the leading cause of air crashes around the world.
All those safety features later, the first thing is it was in the wrong plane at the wrong altitude. Nobody knows why and whose fault that was. Given that there were no mayday calls, one would assume that the pilot was in perfect control of his plane and might have thought he is on the right path, or at least the former. Or it could be that he was too busy trying to find out what he needs to do while having no visual references because of the low cloud cover. This is referred to as loosing situational awareness--a very bad news when you are near a mountain. Its possible he miscalculated his speed, punched in some wrong figures in the computer, or was focused on something else but the end result is he did end up being away from where he was supposed to be.
Now comes the safety part. All these new technology are God sent for the lost pilot -- or are they? The computer is your best fried since it works out almost everything for you and flies the plane for you. Even when you are flying, it constantly monitors you and advises/warns you if necessary. But get confused by one or do something wrong and you'll be wondering what is happening.
Add to that, more often than you would like to believe, a pilot will actually "disengage" that critical piece of technology that he need at this crucial time. In simpler words, there are pilots who actually disable things like ground proximity warnings, etc because they routinely fly close to mountains and all those alarms sounding are irritating.
An example comes to mind (sorry cannot recall flight no.) where the pilot is thought to have disabled the circuit breaker that warns if a checklist is incomplete while trying to take off. Bad weather and ATC Comm. lead the pilots to forget extending the flaps while taking off resulting in the plane loosing lift and crashing. The point being that, in theory we can say the plane has a safety mechanism that would prevent the pilot doing so and assume the plane is 'safe' but its no use if the pilot (and pilots around the world routinely) pull out the circuit breaker.
This flight reminds me of Air China Flight 129 and looks like an example of CFIT. Of course that is speculation at this state since we have no transcript of the CVR and/or ATC.
