You lose something with a shot clock.
This shot took one minute ten seconds, yet it is one of the most famous shots in pool history and brought the audience to their feet. What would have been lost if he had to fire in 10 seconds?
https://www.youtube.com/watch?v=MxZtYALqIrE
You say we shouldn't be focused on what AZB wants, but instead what the public wants...then you talk about a hypothetical public that just happens to agree with your own opinions. And yet you state them as facts, as if you had done extensive market research or traveled 30 years into the future. I have no problem with you having your opinion and voicing it. But at least acknowledge it is an opinion and that a 20 second shot clock puts you are in the minority.
As for what the public wants, it is far from scientific. Hole card cameras made texas hold'em explode into a world wide phenomenon. Not a shot clock. In fact, some of the most entertaining moments in poker was watching someone make a tough decision for all of their chips and going into the tank, analyzing the hand, prodding their opponent for information. It was suspenseful and if you were rooting for one player or the other it was one of the most enjoyable parts of the broadcast.
As for me, I personally would struggle with even a 30 second shot clock. I played bar table 8 ball yesterday for about 4-5 hours getting ready for a tournament. I had my break dialed in and have never run so many racks from the break in my life. I ran 4 racks several times, and more 2s and 3s than I could count. I'd imagine my break and run percentage was over 60%, probably in the 70s. If I didn't run 50 racks total from the break, I was closer to 50 than to 30. I say this because while I'm not an elite player, I know the game. And yes, most of my shots were played pretty quickly. But after the break I might take some time, if I got into trouble and had to figure out which way to break open the balls, etc. I didn't play slow, but I know my game would've dropped drastically had I been playing with a 30 second shot clock. My goal is to play my best, and I don't see the need to sabotage myself for some fictitious public audience that isn't going to watch either way.