There are many more ways to make a character unique than nerfing an ability score. I see a lot of lazy players think a character flaw is just a bad ability score, but that is not true. A good character's flaw is based on their behaviour, their decisions and ideals. Having a lower wisdom on a cleric will not make them any different, just worse at what they do. Having a cleric be, for example, easily fooled into trusting people claiming to follow the same god, or having them be pulled down by prejudices instilled in them by their clergy makes a far more compelling character.
The biology argument is also flimsy. Things like a Tiefling's fire resistance or Stout Halfling's poison resistance are biological traits, but ability scores are things that are very variable from person to person of the same heritage. To quote TCoE:
Whatever D&D race you choose for your character, you get a trait called Ability Score Increase. This increase reflects an archetypal bit of excellence in the adventurers of this kind in D&D’s past. For example, if you’re a dwarf, your Constitution increases by 2, because dwarf heroes in D&D are often exceptionally tough. This increase doesn’t apply to every dwarf, just to dwarf adventurers, and it exists to reinforce an archetype. That reinforcement is appropriate if you want to lean into the archetype, but it’s unhelpful if your character doesn’t conform to the archetype.