Oh, boy… You are not going to like my answer for this.
Im my experience, I have found that it’s usually the user’s preconceived expectations both as a scuba diver and as a land-based creature that often lead away from what actually is the optimal solution.
For example, you mentioned something about your golf bag being much more ergonomic than your back plate and harness. Well… Your golf bag is not designed to be used underwater. Conversely, believe it or not, your back plate and harness are not designed to be used on land!
No one will argue that a backplate and harness is both uncomfortable and inconvenient on land. But seeing as it’s on-land use makes up 0.3% of its total use, it’s not optimized for that.
. It’s optimized for functioning in the water, where most of the weight is being carried by the water, not by your body. It’s purpose is to hold everything in place from movement, not to support weight.
This is extremely common from new scuba divers, and even experienced scuba divers new to technical gear. It does not work in a way that is intuitive for such people. It really does take some experience and possibly some mentoring to really understand how to work with it.
Take, for example, your observation that a misconfigured harness will make getting to your valves more difficult. That’s very true. But the problem is not with the concept, or even the particular hardware that you have at your disposal. The problem is the way it has been set up relative to your body and geometry. Unless you are an highly-unusually shaped person, it can be made to work where everything is positioned right where it’s supposed to be. There are people who are 5 foot 4 and people who are 6 foot 4 and use the same equipment, and can configure it to work properly. The same as true for 130 pound and 330 pound people. (ETA: Not the same equipment without change. In other words, each of those people can configure the same model of backplate with the same type of harness to work correctly for them. You aren’t going to be able to move a backplate and harness from one of those people to the other without reconfiguring it, but the same equipment could be made to work for any of them.)
You are very correct to observe that misconfigured equipment will not work well for you. However, it’s rarely the fault of the fundamental design of the equipment.
I can’t tell you how much tech gear I have bought from people who sold it to me cheap saying, “this stuff is garbage: it works terribly and I don’t understand why anyone would want to use it.” I’m grateful for such people: I get equipment cheap that way.
It always surprises me, though, that nobody ever asks the opposite question: “how come a great deal of very experienced divers can dive successfully with this equipment, and I can’t? In fact, they *choose* to dive with that equipment. Why?” When a person reflects upon that a bit, it might lead one to question some of the preconceived ideas and assumptions that they have made as part of that process. After all, some of those experienced divers are also very intelligent as well as talented designers. Is it that they can’t see the problems you see? Or is it that they don’t experience those same problems because they approach the solution from a different direction?
Back plate and wing configurations rarely work out of the box, and will almost always require a number of dives to begin to understand the concept. Like I said, a mentor can go along way in accelerating that process, but even without that, it can be done on your own. but it demands a different style of thinking and a different style of diving. That’s why people use it: to facilitate those differences. It’s not for everyone.
In the end, there’s absolutely no requirement that you dive a back plate and wing. Millions of people jump in the water with a cushiony, comfortable jacket BCD and live to tell the tale. Heck, they greatly enjoy everything about it. And some people can even do it with decent trim and buoyancy. And there’s no shame in that whatsoever.