IMO, no. In fact, I find added value in the leg protectors being there, as I can't stand a chewed up cabinet.

I think Chris Hutchins documented restoring a NIB No Good Gophers that Pat Lawlor himself owned and sold to a collector, and that machine was stored in a less than ideal location (or locations), and had corrosion on metal parts, and also some lifted inserts, and as I recall, it was NIB.

Can you just restore and shine the metal parts on top of the playfield and make do with some less than stellar quality metal on the bottom side?

When using the Stern style metal protectors you must be careful to fasten the legs squarely to the cabinet, as you can tilt the legs before they are tight and touch the cabinet with a leg corner, possibly putting a nick in the art. Sometimes I use some thin carboard as protective shims during the inital mounting process to insure the legs are spaced equally on each side of the cabinet and contact with the art does not occur. I also deburr the legs with a file before I install them as sometimes when they are stamped, the stamping process will produce a sharp burr that will be pointed right at your cabinet art (not what you want).

So have I.