I have sometimes left the bark on rose shoots.  It starts to peel some during straightening, bubbles up and sometimes flakes off, but I just sand it away. Once in awhile it will start to get crumbly during use, but I sand and seal again. Rose has a pretty thin bark after drying though.  Never tried it w/ any other shoots.  I'd say some guys peel bark off because they need to, to get the weight even on their set of arrows.