I very much agree with the "baby and bath water" analogy. 2e threw out all the stuff in the back of the original TRO 3026. 3e threw out 2d6. AToW threw out 2d10 to get 2d6 back, and random rolls for character generation (that should have gone, in my opinion). I can't speak to the other system.
I appreciate your position on GURPS. I didn't take any of your posts as advocating TPTB do that.
Mechwarrior 1 was not much of a RPG it was at most a pilot simulator. And to be fair not even really good at that.
I think that every incarnation of Mechwarrior to date has been an overreaction to issues with the previous edition.
Mechwarrior 2 was an overreaction to Mechwarrior being perceived poor RPG so they used a variant of the Shadowrun RPG.
MechWarrior 3 was an overreaction to complaints about the power gaming aspects of Mechwarrior 2
AToW was an overreaction to complaints about the random tables in the Lifepath system and underpowered character of MechWarrior 3
Destiny was an overreaction to complaints about the complexity of AToW.
The track recorded for the Mechwarrior RPG is to not try to fix anything, it's to throw it out and start over.
The funny thing is almost all of these editions could have been fixed if some work was put into them.