Splitting the stats as such is a 'huge' penalty for any class that actually wants to use anything that crosses the boundary (such as being able to cast high level spells and have a good dc).
It makes high level casters need yet another high stat, which is above and beyond what the normal fighter type would need.
Fighter type needs either str or dex, and then con, and then whatever else for the character concept.
Caster needs high casting stat, and then high con, then a decent dex, and then whatever else they need for the character concept.
So they start off behind, and all this change does is kill whatever archtype most spans the two stats.
Whatever the problem is that this would 'fix' is likely to have dozens of other changes that wont simply nerf too large of parts of the game.
It makes high level casters need yet another high stat, which is above and beyond what the normal fighter type would need.
Fighter type needs either str or dex, and then con, and then whatever else for the character concept.
Caster needs high casting stat, and then high con, then a decent dex, and then whatever else they need for the character concept.
So they start off behind, and all this change does is kill whatever archtype most spans the two stats.
Whatever the problem is that this would 'fix' is likely to have dozens of other changes that wont simply nerf too large of parts of the game.