As an engineer it is quite obvious that Nikon choose materials for a lens from many years of experience.
If you bump an aluminum lens hard it will get a permanent deformation and or break.
At will be rendered useless,,,
If you do it to polycarbonate it springs back into the original shape or break.
Often the lens will still work until you can get it repaired,,,
From an engineering point of view and for tough professional use the outside polycarbonate with internal housing of the optics in a cast aluminum or magnesium design is optimal.
Repairing and working on lenses for many years it is quite apparent that the current 1.4 AFS lenses and the fixed FL longer lenses, will be very sturdy over time due to no extension of the outer lens housing, the 2.8 AFS Zooms are more fragile due to the extension of the lens tubes and the relative weak design of the internal zoom guides, here you need to always use the lens hood as protection.
Actually looking at lens hoods gives you an idea of how strong polycarbonate is, old aluminum lens hoods are bent out of shape extremely easily,,,, The polycarbonate lens hoods stay in their shape or break at the mount,,,
On a general note:
Please feel free to enjoy old and new MF lenses most us here have our shelves full of them,,,
The same goes for the plastic lenses,,,
However stating one is better than the other is plain wrong!
The 28mm 1.4 AF-D is a nice lens for environmental portraits and reportage PJ style shooting, not for nature scenes as a general lens - sold mine years ago, the new series of 1.4 is vastly superior.
Seems to me your focusing way too much about focal length! Instead focus on lens signature!
If you want the best and strongest all round Manual Focus lenses you should switch to or add a Leica M camera to the kit an buy their Lenses!
They make 21mm 24mm 28mm 35mm 50mm 1.4 lenses that you seem to like,,,
The Leica 35mm 1.4 ASPH FLE is the only one I currently own,,, and it is a engineering photography marvel!!! All hand build! Very similar performance to Nikkor 1.4 series but a little better image quality, yes they also cost three times as much,,
They also make slower lenses like their 24mm I have, no distortion and sharp wide open at 3.8 over the entire frame! These lenses you don't need to stop down unless you like more depth of field! They take photography to an whole other level! Especially for us who love photography as a profession and a hobby.
The Leica M 50mm APO 2.0 is even better than the Otus 55mm!
Leica M lenses are build to another philosophy, they are build to be compact / portable and outstanding.
