I've found that having multiple bars is a nice luxury to have.
- makes reselling the kites very easy
- makes less wear and tear on your lines
- some locals will keep one bar near new to be used in the storm conditions so that the lines are near new when it's gusty and blowing 40+knots.
- if you have an incident and your lines are messed up, you can swap out bars and clean up the mess later
- I would have to say that there's too many of us out there that do little or no bar maintenance. I have seen some trim lines, kite lines, swivels, etc... that are all accidents waiting to happen.