Tradition aside, the problem that I see with this is that the two ends of a jo are identical. The only distinctions between them are fleeting, situational, and relative to your body: thus, it's "my rear hand does this" or "slide the front hand out to the end" and like that. If you try to change this to "take the jo by the red end", sooner than later the ends will be reversed and the red end will be the wrong one to grab.
That seems to me to be a bit myopic. It's not strictly about color. It's only a means to assist in learning. After some time, the colors will mean less because the moved will be innate.