Well, I think the question may come down to, "What do you need to know to be a "good" diver?" (Which, of course, then poses the question, "What IS a good diver?") There are a lot of people who come out of their houses every morning and get in their cars, and drive carefully and conservatively and defensively, but may not have any clue how a distributor works. They can operate the vehicle when it is working correctly, and recognize when it is not. They are safe drivers -- for their purposes, it's not necessary to know a great deal more.
Someone who is going to race their own car is likely to have to know a great deal more about driving, and about automobile design and maintenance and repair, than a commuter.
I don't think you have to be able to regurgitate the ideal gas law, or even name the various parts of it, to be a good diver. You DO have to have a good understanding of compression and expansion with depth. You don't have to understand m-values to plan and execute a safe dive, and you don't have to be able to field-strip a regulator, so long as you are willing to lose a dive now and then when something doesn't work. I know people who don't know anywhere near as much as I do about the physics and physiology of diving, but they are good divers and they know FAR more than I do about critters and marine ecology.
I think the OP was talking about being happy at having gotten the training and experience that allows him to do the dives he enjoys, and not feeling any need to go deeper or scarier or underground, and that's admirable. One of the best instructors I've been fortunate enough to work with told us, "Do all the diving you can do, with the certification that you have, and when you get bored, then go get more training." I remember, when I first came on ScubaBoard, there were articles on the front page, and one of them was, "What to do when you're tired of blowing bubbles." The authors thesis was that eventually, most people will get tired of just swimming around and looking at fish, and that when and if that happens to you, you have to find something else to invigorate your diving. That might be teaching, photography, or technical or cave diving, or REEF surveys, or any number of things. But until you get there . . . blow bubbles and enjoy it!