This is probably the main reason they're so popular now. The Glock is the AR of the pistol world. And they became popular initially because when they debuted there weren't really any other pistols with the same simplicity and ease of operation (in addition to reliability, etc).
And considering the awful grip ergonomics, they're probably all masochists too.
I actually had a similar analogy but different. Having experienced many types of pistols during my time as a private gun owner, close protection operator serving in Afghanistan and now a city police officer I have come to the conclusion:
The Glock is the AK-47, as the SIG P229 (for example) is the AR.. I have always compared those types of pistols as they are very different.
The Glock (in my personal opinion; and yes I do own two of them, and carry one on my side at work) is a piece of crap. Harshly put.. It is a simple idiot proof, dead reliable, pistol with interchangable parts, low maintenance and due to all this a very clumsy inaccurate pistol by comparison. But remember, this is exactly how Gaston designed the pistol.. For an idiot to pull out the gun, have it go BANG, and hit what the operator aims at. So this being said, the firearm performs as advertised and does this very well.
The SIG is the AR-15, more moving parts, higher maintenance, tighter action, way higher level of accuracy, the operator can manipulate all functions of the firearm via the hammer, decoker etc; in my opinion the selling feature of the firearm as this is a professional's gun.
Many have stated due to the all metal parts, and tighter action requires lots of lubrication making it a non-desert friendly firearm. Well I am an anti-lubrication theory type guy for both my ARs and Sigs, and never had any problems in the desert and more SF guys were using Sigs then anything else in those regions with no issues.
Rainman