You don't need to be a sports physical therapist to apply common logic, tbh.
Everybody knows strong muscular legs help avoid injuries, and a strong lower body is very important in basketball for bigmen banging down low, tbh.
In Smith's case it is particularly weird because he seems to have such a strong upper body compared to those legs, unlike like a Durant who is skinny through and through. I can't help but wonder just how much upperbody weight those legs can carry, tbh.
In any case, it's not a deal breaker for me (heck, my favourite target is Poku), I'm just saying there's no way having skinny legs is better than having strong legs, tbh.