I commute on a racey bike I cobbled together with a 50/34 12-25 11 speed. It excels at letting you dial cadence if spinning is your thing. I was surprised at the earlier inforgraphics, from 75-90 rpm. I cruise at 90 rpm nearly 100% of the time, and when on group rides or playing in traffic, regularly get up to 110 or 120, and even higher on the trainer. the jump in each step is nearly 5% in some combinations, meaning one gear brings me from 113 to 108 cadence. for me, I LOVE to dial it that close - when sustaining high power over 1+ minute or even 3-5 min efforts, it makes a noticeable impact on perceived effort and comfort.

for the average sporty rider, the 50/34, in addition to being a better climbing gear, is designed to make an 11-28/32 cassette rideable for the average consumer. 53/39 is just too tall for *most* folks, in most road situations. also, triples on road bikes are out of fashion.