Quality suspension components, chassis design, engine power output, brakes are all areas where a SS will outshine other class bikes. You might argue that a SS power output is not as usable in urban riding but lawdy when it hits 18k RPM I transcend to another dimension.
Comfort, practicality, usability(?) are all areas where a SS suffers without a doubt. In fact, I'll be picking up an MT09 by the end of this season. I'm going to be at the track every other week and I am not swapping bodywork everytime this year too. If I'm going to have a second bike, I am definitely not going to be picking up the same class. Where's the fun in that?
Definitely agree with you; the modern motorcycle market is stocked full of goodies. But sometimes people just want to get an SS for the looks, or the sound, or to look like their favorite racer. Either way, who are we to judge how someone enjoys this hobby?