What investment? I only ask because you said "rolls". Rolling stats doesn't seem like an investment to me, even if you "arrange to taste".
It's an investment if you didn't roll the exact same value for everything and had to make a choice.
I would really love to see an experiment with to-hit being removed from ability scores. The tyranny of the to-hit modifier is such a big deal across the game. I'd still like for there to be a clear advantage to using the standard stat for a class, but for it to be less of a required thing. Along with that, each ability score needs to have something to offer to every class in every party. Reigning in Dexterity becomes just that much bigger of an issue here, though, as well as Constitution to some degree.
An Old-School DM and I have been talking about this quite a bit. He favors Ability scores as requirements for various weapons and armor, etc. As an aside, he would then get rid of class restrictions on such things. Thus, the reason the wizard doesn't use the longsword is because he doesn't have the 14 Str to do it well.
I'm wary of anything that RESTRICTS you from doing things, especially since magic usually provides a way to ignore those in D&D - like how in 4E you could replace just about any skill with an Arcana check with the right options.
Instead, I'd like to see ability scores act strictly as enhancements, but enhancements that apply to everyone, even if those enhancements aren't universally useful (say, a ranged damage increase doesn't help a generic barbarian much, but it can come up against unreachable targets just the same). Some restrictions do make sense, but too many restrictions only serve to prevent interesting combinations.
So it was a flaw in 4e, but no problem whatsoever in Pathfinder, 3.5, 3rd, 2nd, 1st, B/X, etc.? Because ability scores modifying to-hit, damage, and saving throws has been in the game in every single edition.
Regarding 3e, a high primary stat didn't directly change your "to-hit" or damage, but you needed 10+spell level in it to cast the spell. The saving throw DC was also changed by the primary stat. You also got a lot of bonus spells for a high primary stat. With 20 int you get two bonus spells for level 1 and your spells are nearly impossible to save against.Um, no. In AD&D, stats had a much smaller effect on accuracy that kicked in around 16 and never went above 2 (except a +3 at 18/00 exceptional strength)
In 3e, non-finesse melee fighters did get to add to accuracy and damage with a single stat. But not spellcasters, whose high casting stat did not add to damage, nor ranged & finesse weapon users, who needed dex for accuracy but strength for attack.
after a certain point, 3e strength fighters just automatically hit, or used power attack to reduce their attack bonus.
It was only in 4e, where prime characteristic always added to both accuracy and damage, and accuracy always mattered, that the 18 is king (or 20 is king) became a thing.
Nobody objects to the idea that a strong character is better in melee. And if you add strength to melee damage, that remains true. But in 4e, prime requisites mattered too much. And I'm sorry to see DDN going down that road.