Get it all the time.
"I had a (insert year) Bonneville, back in the day."
My normal response is "So did I. They are really different now though."
Can you imagine how well we could have gone back then with modern suspension, tires and brakes? Today's tires, even sport touring ones, are better than what passed for race rubber back in the 60's by orders of magnitude.
Not to mention, of course, that 40 HP defined a "big" bike back then. Now, the 125 HP of my Sprint feels mild. Used to have to wind out third all the way and then speed shift to fourth just to make ton up. Now a simple twist of the wrist from 80 in 6th, hold a couple of seconds and the ton is there, as is 1/2 again that.
The good old days were wonderful and, with the exception of stuffing myself into the weeds a few times, I wouldn't trade the experience for anything but, don't ask me to go back to mediocre brakes, rock hard tires, chains that wore out in 3K miles and lighting systems only a step above a large candle.