I can't tell what your knowledge of straight pool is. You played in a pro event it seems so maybe you're more knowledgeable than me, I don't know. Let me say upfront that I, too, never saw him play, but my father saw him up close on numerous occasions and I've heard the descriptions from him throughout my life as well as from some in this forum.
What did Mosconi do better than anyone today? He made it look easy. Plain and simple. Nearly every shot was a duck so pocket size didn't really matter. Occasionally, something unexpected would happen and he'd kind of get red in the face and circle around the table a few times as if he were upset that the balls misbehaved. Then he'd call something out of the pack and blast it in.
Another observation from my father: Mind you this is in the 60's when he was retired and already recovered from a stroke. The guy, you could argue, was not even in his prime. Anyway, it looked so easy that my father began to question whether billiards really was a game that required much skill. In other words, if this guy can run balls this effortlessly then it must not be that hard to do and anyone could probably do the same. That's how easy Mosconi made it look.
Fast forward 30 or 40 years and my father took up a renewed interest in pool after I moved back into town from living out of state for many years. He watched all the pros on Accustats and youtube and we went to a couple of tournaments together. He appreciated the ability of today's pro players, but candidly always told me it was a joke compared to Mosconi. He was tableside when Appleton set the record high run of 200 balls in competition. He said that run was the closest thing he had seen to a Mosconi type run.
You might be interested to pick up Mosconi's autobiography. There are some interesting stories in there. I think some of what you said has merit, but like always it is hard to compare eras. I think you are putting too much emphasis on shot making and mental toughness of today's players. Mosconi may have been the best shot maker of his time, best strategist and was certainly the toughest mentally.
Let's flip it around. How many of today's best players...
* Played the reigning world champion and celebrity Greenleaf to a close match at the age of 6,
* Beat many expert (professional?) players before his age hit double digits,
* Played for food. There was a time when if he didn't win he didn't eat,
* Walked into a strange pool hall and ran 100 balls on command on a strange table, in front of a large audience, and did it hundreds of times. Think about that. How many pro players today would take you up on a bet to do that?
Anyway, it's an interesting topic to kick around. Gotta run though.