What's wrong with an elf having 20 strength? Even in Tolkien, just because they weren't walking around looking like Charles Atlas on creatine powder, they were still smithing plate and going toe-to-toe with things like trolls. Finrod literally wrestled a werewolf with his bare hands and won. The notion that X race should always cap your capabilities below Y race is silly, and doubly so when we're talking about PC adventurers/heroes from those races.