For example, the F15 was originally designed to be a purely all-weather air-superiority fighter.

Yeah, and the F-16 was originally designed specifically to be a highly manoeuvrable, rapier-like lightweight fighter built to fly circles around the F-15. It achieved those things, mostly, and since then turned into a multi-role tactical aircraft that can perform a whole bunch of different roles.

Same with the F/A-18 – originally designed to be a fighter, and then later it was discovered that it could perform both an attack role and a fighter role in one airframe. The original plan was to separate out the fighter and attack roles into two different airframes with different avionics.

The problem with the F-111 is that it was always designed from the beginning to be a long-range interceptor AND a bomber. That doesn't work, as people are discovering now with the F-35. The idea was the same: save costs by using a single airframe with common components. Didn't work then, doesn't work now.

It is certainly true that people find unexpected uses for weapons systems beyond their original design. I agree entirely. But that isn't my point. The point here is that a weapons system designed to do many completely different things, will fail to do any one of those things particularly well.

I agree with you about the naval version of the F111, in that as a multi-role mission it was unable to perform as designed. But really, what weapon system ever performs as designed straight off the bat (with possibly the exception of the brilliant A10 Warthog)? For example, the F15 was originally designed to be a purely all-weather air-superiority fighter. However, was subsequently reinvented as a ground attack system with the development of the 15E Strike Eagle.
Once the powers-that-be determined what the F111 (and the FB111) was best at – low-level strike bombing – then it became the best weapon system for that role.
Plenty of weapon systems that started out not as expected, and redeveloped into the best in their field through working on their strengths. Just look at the history of the M16 assault rifle as an example.

The basic premise of the F-111 Aardvark was to perform as a multi-service, multi-role fighter-bomber that could both handle stand-off naval defense needs using those huge Phoenix missiles, and Air Force ground-pounder needs with a big bomb capacity. It was never able to do that because a fully loaded F-111 was so heavy that it could not perform a decent carrier landing safely, which is why only one such was ever recorded.

The Air Force version worked well, certainly. But the F-111 could never perform a multi-role mission – which is what it was designed for. Hence, on that simple basis, it failed to deliver.

POGO? Pogo was founded in 1981 to murder the M2/3 and M1, quite possibly on behalf of the Soviet Union. They're neither insightful, nor intelligent, nor especially honest. Example, one criticism of the M2 was that the Army didn't shoot it from certain angles in testing; Oh, wicked, evil, and deceptive Army. Ummm…no. There's no need to waste an expensive target on a shot THAT YOU ALREADY KNOW WILL KILL THE VEHICLE. Pogo somehow neglected to mention that. They're frauds, start to finish and top to bottom.

The other tanks are just as expensive as, or more expensive than, the M1. Europe has been selling off most of their fleets at rock bottom prices because Europe has disarmed and has a lot of surplus hanging around. The M1, largely because we've built so many and used them so much in peace and war, thus working out all the bugs, remains the class of the world, tank-wise. We don't even know yet if T-14 is anything more than a soft metal mock up. Yes, really. M1 does use a lot of fuel, but this is only a problem for the logistic incompetents of Europe. _We_ are the logistic masters of the world and have no problem with keeping it fueled.

According to defense news

By the early 2030s, the viability of the entire U.S. nuclear deterrent is at risk from an inability to produce tritium for nuclear warheads

This leave the US vulnerable to a kill shot since our ability retaliate is limited

If Russia or China pushed too hard hit a US production with EMP weapons , bioweapons or anything else with enough boom and watch the society implode along it natural fracture lines of culture and ethnicity