My husband pointed out my GF Hifi does not have cable housing on the all the cables, obviously a GF design but they seem like they shouldn't be running naked. Does this matter? Should I get some cable housing installed? Finally, how much does it cost to do those? I have seen some flashy looking bikes at the races so I guess I could do white, black (to match the other) or pink.

For illustrative purposes the cable without housing runs on top of the downtube. It does have little rubber eyelet like protectors.