I think it varries from person to person.
I have a collection of AF zooms, but all my primes are MF.
I use them differently. When I travel if I want to take a lot of stuff, it usually boils down to 4 AF zooms. Sigma 10-20, Pentax 18-35, Tamron 28-75 F2.8 and Sigma 70-200 F2.8. THis goes along with 2 bodies and 2 sitma TCs for the 70-200 plus a flash
I may also decide to take my SMC 300mm F4 and 1.7x AF TC.
Just add up the weight and volume and this is about the carry on limit for an airplane
I have travelled light twice, with what I consider good success, by cutting this list down somewhat.
My light kit is the 10-20, the 28-75 and
one other lens plus only 1 body and no flash. It goes in a backpack with my other carry on stuff, and to walk about I have a shoulder bag that holds the 2 lenses that are not om my camera.
The
one other lens is the point. I have taken my 135mm F2.5, and my 85mmF1.4 (along with my 1.7x AF TC. Both have performed very well but I am tending towards the 85 mm more and more because it offers a lot of other advantages, and with the 1.7x AF TC can give the same reach etc as the 135. I have also considered my 50mm F1.4 for night shots, but I have found that the high ISO of DSLRs (compared to film) is so much better, that speed is not that important.
The MF lenses make light travel kits, but will not replace my AF zooms because they perform so well, but note the zooms and AF lenses I use are fairly high quality to start with.
the main use of my MF lenses is when I go ouot to have fun, around home. I just grab one lens, and go out. I force myself to take shots with only that lens, which makes you think more about what you are doing.