Welcome!

I see jimping as a personal preference kind of like large vs small vsc no choil. Ic will agree that it likelyc is ad cost factor. It would take a bit more machine time to jimp the spine. There is also the issue of where and how to implament fthem to cover everyones preference. The number one reason is most likely tradition, none of the yardsf other releases have them (whtich goes backc to the least cost for best product goal),