As to ride quality and handling, I can only speak for actual comparisons to modern vs my 1990 tourer, which is most likely pretty close to 80s frames.
But no matter the bike, there's fork and frame rigidity that improved, the racks, the bearings, the cranks, the number of speeds and gearing range and jumps between shifts, brakes.
Stuff improves, that's life.
but if you're enjoying yourself on whatever bike, that's great.
I used to have a 1989 Miyata 1000LT and a 2003 Trek 520. I only needed 1 touring bike, so I sold the Miyata and kept the Trek. The Trek is a little more rigid, but the Miyata had a much better ride. Very good unloaded and sublime loaded up. If anything I regret selling the Miyata and keeping the Trek. The Miyata was the better bike.
I do think disc brakes are a substantive modern improvement on tourers.