Ability Scores, Modifiers, and Saves

I constantly tinker with rules. I've never found a game system I was 100% satisfied with, and I cut my RPG teeth as game master for possibly the most house-ruled, seat-of-the-pants GM ruling game ever made; Rifts. 20 years later (fuck) and I am still doing it. Albeit with DnDish rules now. Ability scores are lame. They have two functions; to provide a modifier, and to roll against if the GM