There is one thing that Gary inarguably designed himself that was part of the LBB version of D&D, and every version since: The alternate combat system. Even 3.x, 4e, and 5e have kept it, only flipping the scale to ascendng AC.

Gygax had his faults. They are many and well documented. Being overly focused on them makes ones analysis of his work just as untrustworthy as pretending they don't exist.