The sport tourer of the early 70's may have been an anomaly but it was a huge one. The tens of millions of bikes sold from 1970-74 pretty much supplied every teenager and young adult in America with the bicycle they needed for the next ten years. The bikes were easily handed down to younger siblings or another generation. The bike industry almost had to switch to a completely different bicycle just to stay in business, hence the mountain bike, bmx bike and the racing specific bike. There were still great Japanese built sport tourers coming over in the late 70's and 80's but demand was not big enough to keep a shop open without those other bike types in the mix.
The sport tourer was a great design for the vast majority of riding being done; which is basically recreational riding. The one overlooked feature were eyelets. We Americans never figured out what fenders were and simply adapted to riding all wet and covered in grime. It's still true today, most of my riding friends from the 1970's still eschew fenders no matter how miserably they suffer.
By 1993 there were few good choices for recreational road riding in bike shops. Instead of the hard tail mountain bike there was the full suspension downhill racer, instead of a sport tourer there was a racing bike with hard skinny tires, low handlebars. Neither bike style could mount a rack, fender or bag.
Things have gotten a lot better since then but I still see bike shops selling racing style bicycles to 60 year olds who are replacing their old bikes. We then have to swap out stems and gears and derailleurs just so they can ride them and then they ask how do you carry stuff.