Skills. With skills, why spend so much of the books and so much design time (DM-wise) on rolls that are either never used or nearly always succeed?
Feats. Remember when someone in AD&D took the fire-building proficiency? Suddenly nobody knew how to build a fire any more except that one guy. Feats are like that to me. Any time you make a list of things one person could do, it also becomes by default a list of things everyone else can't.
Ability scores perfectly mapped by a mathematical formula to ability bonuses. Why bother with ability scores any more? Just use the bonuses. Oh, I know they use them for feat prereqs, but see above.
Feats. Remember when someone in AD&D took the fire-building proficiency? Suddenly nobody knew how to build a fire any more except that one guy. Feats are like that to me. Any time you make a list of things one person could do, it also becomes by default a list of things everyone else can't.
Ability scores perfectly mapped by a mathematical formula to ability bonuses. Why bother with ability scores any more? Just use the bonuses. Oh, I know they use them for feat prereqs, but see above.