Then say that.
And then we need to admit that we're back to square 1. Square 1 being:
The only way to achieve spellcaster : martial parity (particularly as levels accrue and arcane power surges upward and outward) is (a) GM Force in the way of the classic (brutally obnoxious in my opinion) premptive or post-hoc block tropes that we're all very aware of (rampant...stealing spellbooks and components, anti-magic fields, anti-teleportation circles, counterspelling NPCs, etc) and/or (b) heavily GM-curated play where they have a massively disproportionate role in the trajectory of play with "tailored encounters" and "spotlight dispensation."
Going back to that square 1 is a non-starter for
@Campbell (the thread's starter) and many, many, many other players of D&D and its offshoots.
Well, i think what we hae here is differing objectives and differening perspectives.
I too have played more than a few unreliable magic games and sorry, it did not suddenly provide this balance of amorphous feelings that seem to be seeking. Nothing close.
To me, though, straight up,the notion of what seems to be the desire for sandbox play
and balance of feeling
and balance of complexity of skilled play across the pc choices is impossible. You are removing the primary driver of balace, GM "curation" of the challenges and plot elements to show sone off the strengths and differences of each character being vital.
Once you remove that dastardly GM curation, you wind up with so much player control of the challenges they face that its no longer possible to spotlight or highlight each character in turn unless they choose it.
Exception - if the pcs and players have significant power that is non-defined such as scene edits or amorhous powers-on-demand by gimmick points and the like. But, as observed, that style of gaming seems toalso be unaceptable to many playing this kind of "specified traits" char-gen game.
It seems to me that the three things being sought - pre-specified abilities, mmm o or minimal GM curation of challenges/sandbox, all these different bslances and feeling - are not simultaneously providable by a system.
In a game of pre-specified abilities divisions, you need GM assisted balance to get that balance. In a game with amorphous gimmick point scene edit "spend to solve" mechanics, that becomes irrelevant and the "manifested solution type" just fluff.
"My barbarian in rage punches wall, spend gimick point, exposing a secret compartment with vital clue."
I have yet to see a game that produed all three.