I tend to think of sport-touring more as a riding style than a type of bike. Stay off the freeway, ride briskly in the twisties, and put in 500 mile days minimum. I "built" my first ST before you could really buy one (except maybe an R90 or 100RS with Krauser bags). It was a Honda CB900F, with a special-order factory Sport Control Kit (lower bars and rear-sets), a Krauser hard-bag setup, and a Bagman tankbag. I even would put on a Windjammer in the winter, with a cut-down screen. I put almost 50K miles on that bike in 4 years and then bought a factory-built ST .... a K100RS with BMW bags. At the time, the balance of sportiness and distance capability was perfect for me. But as I have gotten older, the upright ergo's of an Adv type bike are better for me, and I also ride slower and don't need the speed-friendly riding position and wind protection. I think most VStroms and GS'es are ridden as sport-tourers. I mostly ride a VStrom now, and think I'll probably have an Adv type bike as my main ride as long as I keep riding.
I do see quite a few Concours and FJRs on the road though, usually during commute hours. Most of the RT's I see are black and white and ridden by guys with 3/4 helmets and short sleeved shirts in the summer, usually sitting by the side of the road and occasionally practicing tight U turns,