Just because the USGOV is powerful doesn't mean it is invulnerable to stupid decisions. They didn't learn from the F-111 and went out to make another all-in-1 plane. That never works. You can't make a design that incorporates the design of a V/STOL aircraft without severely limiting the performance of all versions.
No multirole jet designed to be multirole has ever succeeded as such. The F-4 was a navy interceptor adapted to other roles, and it was incredibly successful. The F-16 was a pure bred dogfighter - initial versions didn't even have a radar - but it was adapted to a fully multirole aircraft. The F-15 was designed as a "no pound for air to ground" air superiority fighter jet, yet it was adapted to incredibly successful "strike eagle" versions.
The F-111, on the other hand, was designed to be a strike, electronic warfare and interceptor jet, but because it was so heavy and unmaneuvrable it only ever succeeded in the strike/electronic warfare aircraft.
The F-35 will probably be decent at strike/ewar because of its stealth and high incorporation of technology. But it's too slow, too unmaneuvrable and has too little stealth payload (only fits 4 missiles internally).