Originally Posted by
catonec
Only 2 possible reasons, the first is cosmetic appeal, the second would be to change length or angle.
I'll give you a third.
I bought a used bike that had horrible (aka classic-bend drop) handlebars. They had to go, immediately. They had a 26 mm clamping area, and modern bars are 31.8 mm. Replacing them meant a new stem ... which was on the house, thanks to LBS.