Just get rid of ability scores all together. There is often only the loosest and shakiest of reasons of why they affect anything they affect across the character sheet in the first place and despite being treated with equal weight in character creation, a character most certainly does not get the same benefit from investing in each.
1st and 2nd edition saw people tanking their mental stats for physical ones unless they were a spellcaster, 3/3.5 was the age of characters with no Charisma and only average Constitution, 4E had class basically dictate your main two ability scores unless you were intending to render yourself utterly inept, 5E is the age of everyone having super high Dexterity and no Intelligence.
The ability scores were arbitrary from the beginning and while people have tried to create some sort of connection with them in order to justify them-- there really isn't. They just aren't the best array for describing a character and certainly not the best array by which to balance a character for the game. It would be far easier to create a much more balanced game by doing away with them entirely. Most everything one does with them can be assessed by a skill or by creating a skill that does that thing.
Once ability scores are eliminated, you don't need to worry about ability score improvements either. Which, in 5E, means you'll see way more people taking feats which are fundamentally more interesting anyway.