Sounds like you should look into making some homebrew class feature options, if you're unhappy with the official selection. Lots of 3pp options too. I have a compilation document full of them.
Why wouldn't it be, at least in theory? A particular PC may never be in a position to learn any given ability, but theoretically they could under the right circumstances.
I think the assumption you make here that intent should be folded into task when determining the outcome of the roll is unwarranted and subjective. Intent need not have any bearing on the success or failure of any particular task.
I can definitely see your point, and would not to averse to a more granular combat system. I've been looking over Rolemaster recently, and it certainly looks like a more simulationist experience.
You're right, they did their best with what they had to work with. WotC's fans can't decide on what they want the official game to be, and WotC doesn't want to push outside of fan desires (much).