Even though JA had whimsey and humor on his layout, He was doing things that are now considered "normal" in the hobby. Have you seen his structures and the detail that they have? How about his locos? All of his locos were steam and were either kit-builts, kit-bashed, or brass. He wasn't afraid to take a brass loco and turn it into something totally different from anything else available at that time. His 4-10-0 was a good example of this. Here was a loco that had no prototype, but he built it and it was built to prototype practices. None of the detail on this loco was out of line with any other prototype that could be found on the rails. He also required that his locos pull extremely well and run smoothly. If they didn't, and he couldn't correct this, he eliminated the loco.
He also, as has been mentioned, ran strictly to a schedule, and realistic operations. Sure he used tabs on cars, a now primitive mode of operations, but the movements involved with all trains were done in a very realistic manner. I believe that if DCC had been available to him, he would have used it without hesitation.
He was a planner and builder par excellance. He placed wires when installing scenery, that he knew he wasn't going to use for many years in the future. In this case it was wires for signals that he knew wouldn't be installed and operational until after construction was basically finished. Some signals he had gotten installed before he died, but others, just the pads they would sit on got installed.
He was a forward thinker and innovator unlike any that has been seen in the hobby before or since.