One reason might be to prevent flats. I've only had 2 flats in the past year and a half, but both were from breaking a spoke, which then pushed back through the hole in the DTSwiss rim and punctured the rim tape. Regular rim tape (stans, mucoff, etc) isn't good against spoke impacts, but it doesn't leave residue when you peel it off like Gorilla tape. If combined, you get no residue, but also better resistance against spoke punctures.