The advent of the 34 inner chainring coincided with the new mamils who could ride a bike reasonably well on the flat but not so well when the road went in an upward direction. Bike manufacturers spotted an opportunity to supply a mechanism that would, in one fell swoop solve the problem of both making a cheaper chainset by losing the granny ring on the triple, yet at the same time allowing the newbie [in the male case] to still feel macho because they're riding a "double" and not a perceived softy triple. Many of these new cyclists have a 28 cog or more on the rear which in effect of course is a granny gear when coupled with the 34 chainring. Nothing wrong with that, but, and it is a big but, the new compact that was now becoming ubiquitous on road bikes was causing it's own problems, namely the big drop from 50 to 34 resulting in a lot of cross chaining. Watch any sportive and you will see riders in 50x28.
Things are beginning to change, 50/36 is becoming more common which is fractionally better but personally I prefer 52/42 on a double [as others have said]. The triple is really no more difficult to set up and provides a better [imo] riding experience because 90% is done in the middle chainring. Added to this you can easily tailor the chainring sizes to fit your ability.
There is a whole generation out there who think the compact chainset is normal and consequently have never ridden anything else.
