If you were a guy on the ground under heavy fire in need of air support, which would you rather see coming to your aid? As an enemy combatant, which is more likely to make you @#$% your pants? An F-35 10,000 feet above the battlefield lobbing a smart weapon? Or an A-10 swooping in and spewing 4000 rounds per minute of hot 30mm death?
The A-10 is NOT a deep-strike craft. It's NOT designed for penetration of enemy air space. It's designed to loiter and directly support the ground troops right on the front lines, while the hotter and sexier rides take care of the rest. And it does its job very, VERY well.