The TL;DR of the rule is:
The 6 classic ability scores are (allegedly) not well-balanced among themselves. So the attempt is to fix that by:
- Combine Strength and Constitution
- Split Dexterity into 2 (basically, Dexterity: the stuff with your hands; and Agility: the stuff with your feet and body)
- Charisma becomes the stat for Will saves, instead of Wisdom
In short, do you agree with the stated goal of the system? Whether or not you do, do you think these particular changes are a good way of addressing that goal?
Have you ever tried out this variant, how does it go in practice?
In D&D I’ve always seen this statement and thought it overrated to be honest (at least if you’re not running a trap-filled dungeon-crawl). But Pathfinder puts what D&D 5e uses “Insight” for into Perception, which makes it far, far more important. (Of course, it’s Wisdom-based in either system, so the relevance to the relative importance of each ability is the same.)