But isn't it possible that some other idiot takes his place instead? And finds new ways to f--- things up?
I originally posted a more critical piece about your McNamara derangement syndrome, usertron, but it missed the point, so I deleted it.
Instead, using your constant reference to 1962 being the turning point of his baleful influence, I'll state what I believe in the post-'62 counterfactual department; the most likely replacement SecDefs in the remainder of the Kennedy era (whenever that might have been) are Bobby Kennedy and Maxwell Taylor; the most likely replacement SecDef in the LBJ era is the guy who actually was eventually appointed, Clark Clifford.
Clifford is the only one I'd wager is capable of ameliorating what in OTL was McNamara's Vietnam policy, from the very beginning of the second term.
JFK was capable of desiring to have better advice earlier IOTL than LBJ got, but that's where his alternate appointments make a massive difference:
Taylor? Taylor is noted as having dressed down RVN generals as ambassador when he wanted to get his way; he wrote a detailed plan for Vietnam escalation in 1961, when McNamara was still back and forth on the subject; and he was caught lying about this Vietnam policy proposal in a TV interview during the early seventies.
RFK? Bobby's warmaking experience was in overseeing the batshit CIA black ops against Cuba,
after he had first helped create a diplomatic settlement that was meant to avoid formal war with Castro. He is renowned as being the most abrasive cabinet officer in his brother's admin, and it's now generally thought that his ability to be a considerate, respectful leader of men really only occurs because of the assassination in 1963. Also, other than POTUS, he's the civilian who had hands on control during the Missile Crisis, more than any other, despite what you've said about McN.
IOTL McNamara was settled on giving LBJ de-escalatory advice during 1967. There is no reason he doesn't do so under JFK. Maybe his misgivings that already existed during 1966 OTL become leading policy proposals that very year if Jack is still president.
Clifford is most likely capable of reaching this conclusion, as it's his course of action IOTL 1968; these two others? I honestly don't know. If JFK motivates them towards giving him de-escalatory advice, then I'm certain they both volunteer this advice. If he doesn't, then it's up to the vagueries of their respective arrogance/determination/hubris. LBJ won't seek such advice during 1967. Though I can see Clifford cutting through Johnson's bullshit enough to almost get POTUS to that place in '67. Almost.
On other things, maybe Taylor or RFK can assert a more impressive/cooler big ticket item procurement policy for America's anti-Warsaw Pact air doctrine, but I don't know much beyond the TFX cancellation, and honestly I don't know if that's the thing really worth getting upset at him or anyone else (as per the Avro Arrow.)
Vietnam is the big one.
I remember you schooled me about WWII Japanese force projection, and I appreciate that, as I'm not a member of the local military gearhead contingent.
But don't think you can school me about the utter failure of the post-Truman US leadership class to avoid an unwinnable war on continental Asia. That's a human system I've studied a little; it's a dysfunctional political system, not a gearhead or wargamer wishlist system.
It's more than one high profile cog. McNamara was not some outlier.
