The 104 came along when the Air Force asked for an interceptor but really wanted a do-everything plane. The 104 was developed as an interceptor; super fast in a straight line and capable of taking down enemy bombers. At that role, it was very good.
Then the Air Force wants it to be a dogfighter. Then, they want it to be a ground support fighter and find it can indeed hold a surprising bomb load on its razor thin wings.
I hate the fact our DoD insists on a jack of all trades aircraft when the Navy, Air Force, and Marines want very different things. Not to mention the poor Army that just wants some ground support aircraft like the A-10 Warthog; which the Air Force hates because it doesn't go Mach 2 in stealth mode or cost 10 bajillion dollars.
The Army really should have retained its right to aircraft and let the Air Force concentrate on whatever else. The Army would have had more effective ground support in Vietnam and would have had scads more A-10's to send to Iraq and Afghanistan. IMO.