You don't want to make concessions but would you concede that I might perhaps imagine how a fighter and a wizard should/could be different based on my real life experiences which I'm sure are vastly different from your own, but no less valid (keeping in mind we are talking about a fantasy world and hence none of our assumptions about realism need be accurate whatsoever, real life experiences or not)?
Not only will I concede that there may be different conceptions than the one I associate with D&D past, I believe I already said as much before. I've read too much fantasy and played too many different RPGs to think otherwise. My unwillingness to concede alteration on this point- namely, the way in how I believe the gap between magical and martial competence between warrior and wizard
should be- is to be taken to read "within the context of D&D."
Because unless we are talking about generic systems like HERO, GURPS, etc., any given game can only reliably model a few kinds of supernatural stuff before things start to break down.
For example, D&D would be a
horrible game in which to model casters of the kind you find in Michael Moorcock's
Eternal Champion cycle of books because nearly all of their magic is based on pacts with or the ritual summoning and binding of otherworldly beings. And putting that on context of this discussion, that also means that how good a martial combatant a wizard is depends entirely upon the wizard himself...but also as a flipside, whether you can be a wizard at all depends upon your bloodline & race. So the spellcasting is the wrong kind AND "classes" model the characters poorly.
Other authors also adopt the "magic is in the blood" limitation to whether one can be a caster or not...and often, those casters are nigh unto gods. (At least the antagonists are.)
In the Shanarra books, the use of magic is a learned skill, but the use of certain magic items is limited by heritage. Whether you learn how to fight is up to you, but the setting includes very little D&D style high-power combat magic, so many casters are competent.
Ditto to a great extent Harry Turtledove's
Darkness saga.
In
Thieves' World, there are a few different paths to magic, most visibly the Blue Star Adepts. The Adepts gain their powers in part from being subject to a magical taboo- each unique to tie particular Adept- and the Adept is powerless against the being with knowledge of that taboo. Again, each Adept's combat skill is independent of his magical ability.
And I like all of those.
But those kinds of wizards are poorly handled by D&D...and I don't think D&D's core
Wizard needs to be fiddled with to make modeling those kinds of spellcasters any easier. Better, IMHO, to model those kinds of casters with different classes and possibly mechanics (IOW, different spellcasting systems).