Installing a painless wiring system

The kit I was looking at was A Painless, Mopar specific 21 circuit, #10127. I guess the other thing was I came across someone who bought one and sold the car ahead of using it. So now he is saying to get it out of his garage for a a couple hundred less than he paid. So really, again if I was going to do it, now is the time. But the question is still (for me), is it really necessary...