I am no expert, but I listened to a podcast with a couple.
There is a great podcast on meat eater, with a few industry guys, and a vortex rep that talks about this a lot. I would recommend listening to it. The whole meat eater podcast is great actually. I think it sais vortex rep in the title.
To sum it up basically in America 1 inch became standard, and in Europe 30mm was standard. Largely due to tooling and tube stock that was available off the shelf. Not much different aside from a bit more adjustment capability from an engineering standpoint inside the bigger tube. There is just more room, light transmission and all that stuff is too small to be detected by the human eye with all other factors being equal.
It lends itself to certain niche applications, but the vast majority of people 1 inch is more than enough. The rep even said its mostly just people see bigger numbers on the box and that makes them buy it. Most consumers are low information, just being on a forum like this makes you a higher information consumer. This also makes it easier to fit everything in the tube just by volume. As a rule, bigger is not better, there is more to it. Perhaps you can reduce cost of your adjustment apparatus and assembly. Or maybe its the same crap just a bigger tube and bigger numbers on the box.
I do believe that as more and more materials are made over time, and in a global market that all standard measurements will eventually phase out. If you run factory the makes bolts you need two sets of tooling, and the metric is cheaper due to higher volume. I wouldn't even recommend buying standard wrenches nowadays. Everything is slowly going metric in automotive just because the fasteners are a fraction of a cent cheaper. Manufacturers buy these parts by the ton. A true 1 inch tube would be 25.4 mm, so that is just silly to replace that tooling all the time when metric is taking over. Even now the tubes are probably 25mm, and just say 1 inch for consumer comfort and familiarity.
