Hello @Link. The skin expansion is helpful when you have a skin surface with a wall on top of it. Expanding the skin will push the skin further under the wall and this can avoid ugliness if the infill density below the skin is not high. It's also useful for removing small gaps that can occur in skin when a small feature lies on top of skin, e.g. lettering.
The skin removal feature is used to shrink back skin before it is expanded. So if you shrink and expand by the same amount, the result will be the same? Not if any of the skin area becomes so narrow that it completely disappears. That's the main use for shrinking the skin.
Hope this helps.
I used to get this a lot on a work UM2 I abused early on. Try lubing up your rods as well for good luck, worked for me. try to make everything as smooth as you can for the machine. try a few drops of sewing oil on each rod.
P.S. Rotating the model means cura slices it differently regardless of its geometry so might help but may not always be a option. I ended up simply adding oil before each print and printing slower (50mm/s) and that seems to work! I didn't even bother tightening any pulleys on the UM2, but then again I don't know what printer you are using, so may be different.