I believe the pipes you get now are an order of magnitude better! Why? Back in the day pipe smoking was much more popular than it is today. They could not source good quality brier as there was pressure on the resource. Now the quality of the wood is much much higher, because there is less of us and the wood is simply getting older and better before it is hacked down to make a pipe. The grain of today vs what they had 50 years ago was leagues ahead. Now this does not always mean it is a better smoker but it is better wood from the start. Go look at a smooth pipe from yesteryear, look at the grain then go to a high end pipe maker and look at the grain. There is no comparison, what you have for yesteryear is nostalgia, myth and whatnot. 20 years ago it was very hard to find a Savinelli even the rusticated ones like the alligator that did not have fill. Today you can get smooth flawless Savinelli's something that was simply not the norm. It is funny if you consider the pipe is already rusticated so you should not need any filler, but even they had fillers as the quality sucked!
I own quite a bit of vintage Britwood, as well as modern artisan made pipes. I completely disagree with your thesis.
Excellent quality briar XXX plateau was available and used 140+ years ago, just as it is used today. I've seen antique pipes with stunning grain that equals anything on the market today. The reason there is far less in the way of grain queens pre WW2 is because companies didn't cut and shape for grain. That didn't become a thing until after WW2
Besides, you can't smoke grain. I doesn't improve a pipe's smoking qualities, to the contrary, straight grain is structurally weaker than mixed grain. But that's about toughness, not smoking qualities.
One thing companies like Barling and Comoy did that few contemporary makers do, was run their own harvesting, seasoning, and milling operations in Algeria. They controlled the quality from the ground to the sales counter, and they were very committed to quality. The age of the burls selected started at 65 years and went up from there.
Bottom line, excellent pipes are made in every era and crap is made in every era. The biggest differences, to the extent that they exist, are styles and shapes, bite and button design, and airway size. Many contemporary artisan carver have a more open draw than traditional pipes. But even traditional Britwood used variable airway sizes. Charatan straights were drilled at 4mm and the bents were drilled at 4.7mm, very open.
Generalities are easy to comprehend, and often incorrect.