It's very hard to describe the difference between a Ferrari and an Oldsmobile because the cars are superficially similar, but trust me, there is a difference, and it's a big one. I called an Apple phone support technician today and described what I hoped to achieve (menu items with underscored letters for shortcuts). He told me that he also had worked extensively with Windows XP (the last Microsoft OS in with a good shortcut system). He said he too had spent much of the last year looking for a solution which allowed an experienced user to keep his hands on the home keys and manipulate the menu system without spending hours trying to memorize hundreds of shortcuts that are confusingly similar. Microsoft had the best system in this arena by a country mile, but they stupidly abandoned it. I think they were intimidated by Apple. If Apple develops a good shortcut system (not an ad-hoc collection of thousands of conflicting 3-&-4-finger shortcuts), it will be just one more nail in Microsoft's coffin. I'd be very glad to see it, frankly. Part of my distress is due to the fact that I'm working with a laptop that doesn't have the home, end, page-up, and page-down keys. These require taking your hands off the home keys also. It's not hard to imagine a better approach.
It's important to understand that the XP/95 system (abandoned in windows 7, vista, etc) did not entail using function keys or control-alt-shift-left elbow. A key difference is that control-alt anything necessitates taking your hands off the home keys. If you're a touch typist, this is a disaster, costing about five seconds each time it happens. I never used the shortcut "control S" in windows because it required me to stop typing just to save the file. Instead I struck (pressed and released) alt to place the focus on the menu system, then struck F for file (easy to remember) and S for Save (easy to remember). Not all of the shortcuts were easy to remember, but because you never needed the mouse for anything, you quickly learned every shortcut you needed for daily or weekly activities--because that was all you ever used (alt, f, s: save), (alt, e, f: find), (alt, v, z: zoom), (alt, o, f: change font). In Windows, Alt-Tab could be reliably used to switch between windows. The equivalent function in OS 10 works only about half the time, often revealing nothing more than a menu bar, and completely unable to switch between multiple windows launched by the same program (typically a browser). Help windows stay on top, getting in the way of following their directions. I would never say that windows was a better system. That's why I switched; Apple had accumulated too many improvements. Nonetheless, the old windows shortcut system, when properly used, was vastly superior. I used tab and other keyboard shortcuts to manipulate almost all dialogue windows. You say you use only "one-stroke" keyboard shortcuts. I'm a new user; maybe that's why I can't think of any. It seems that all of them require depressing at least two keys simultaneously. It is possible to place the focus on the menu bar but only by removing your hands from the home keys (ctrl-fn-F2): Afterwards, you then go through a tedious and very slow process of reading the menus, decrypting the shortcuts, aligning 2-4 fingers to invoke them, and finally replacing your fingers on the home keys. Using the mouse might actually be faster. In windows, I could work with unfamiliar software much faster. You, yourself, say you use only "one stroke" shortcuts, that tells me that you prefer striking one key at a time, and that's nearly impossible with OS 10 shortcuts. If you tried my way, I think you'd see the advantages pretty quickly.
I stuck with Windows XP for 10 years because I could see that Microsoft was making it harder and harder to use their software quickly. The last versions of Office was simply terrible, recoded simply because that was the best way to milk their cash cow. I think Microsoft is toast.