Well, fstop, let's take a look at your statement:
As the subject was the Nikon F, your first sentence reads as comparing the F's MLU to the MLU's of the F2, F3 and Minolta. Your last sentence reads in context as referring to the F's MLU, which you had referred to as clumsy. You did not say it referred to the other Nikons.
And why did you include "the Minolta"? Which one? The SR-T 101 I used to use had MLU, and it did not require pressing the DoF button. I never tried to do multiple exposures with the F, but I can't see any reason why they would be impossible with the mirror locked up.
Myself, I never found the MLU procedure on the F2 or F3 to be clumsy. A little manual dexterity is all it takes. Very quick and easy.
Your second sentence is wrong. One frame is lost; the mirror stays up and subsequent shots (like say, bracketing) are made until you move the MLU lever back to its original position. If what you meant was for every shot which is a whole new composition, OK- except with the 21mm and its separate viewfinder.