Did you consider 'dump' stats being 'dump' only because you chose them to be? What I mean is, aiming for high CON as a high elf fighter is venerable, but wouldn't aiming for high intelligence be better still? Even as a fighter? You don't need to solve everything by flexing muscles after all. A highly intelligent fighter is far more unique in my book than a try hard consitution-esque pretender of a fighter.
It would be annoying and complex, but if there were some way to motivate builds like that, it would be cool. Something like "this weapon ability is only available to characters with int of 12 or more..."
I'm not recommending or suggesting that at all, but "sorry, your fighter is too dumb/ not dexterous enough/ whatever to do this cool thing" would be an interesting dynamic
