No it wasn't. It was designed to be used without a mouse, that's all. More specifically we didn't want you using an operating system interaction method to control the ship's functions when you're supposed to be pretending to be a pilot handling a ship with a bunch of HOTAS like controls. Thus everything was designed to be done through HAT switches and buttons. We did not want a mouse cursor on top of the screen in space flight as that's the exact opposite of how a pilot in this universe would interact with their ship.
I can understand that. It makes sense for when you're in the ship piloting.
I feel there are two distinct UI use-cases though. Flying and not-flying. The flying part should be fully controllable and optimised for HOTAS, just as you envision. The non-flying should be optimised for "computer", i.e. the best interface for one of them, which is still a keyboard and mouse, should therefore have all the usual UI elements like tool-tips, click-able columns, keyboard shortcuts etc that people are used to.
I actually think the 3-view option for in-flight is a very elegant and a functional solution to that problem and I really do admire how much can be done with it from a HOTAS. The issue I have is that I'm forced to use it for things that would be better done with the mouse, things I would do while not actively flying my ship. For example when I'm flying along in super-cruise in a straight line for 100,000Ls, or the docking computer is flying the craft, I'd like to swivel my seat to the computer terminal and start doing non-flight stuff, e.g. checking prices, configuring module settings, checking my stats or the local news, reviewing my cargo manifest. All things that are much better done with keyboard/mouse. Just as I don't expect to drive my car with a mouse/keyboard, I don't expect to program my sat-nav, or checking my fuel comsumption by turning my steering-wheel and pushing pedals.
If the intention was to get the "pilot" UI fully working and working well, before looking at the "non-pilot" UI, then I can understand that, but no one has ever said that, and I'm left with the impression that in the future you envision for ED, pilots operate Excel 3001, and Firefox 9150 using a HOTAS.
Longer-term, how does this translate/scale to multi-crewed ships? Will the navigator/engineer/gunner also have to use a HOTAS to do non-flight operations?