If you have it, why not just put it in... A lot of times, I wish I had one.
There are so many times I just want to pull into the parking spot and jump out of the car. But I can't due to spool down; especially at autocross events or drag races.
I don't have one because I'm waiting for a PnP to come out...someday.
I agree the MS3 does not "require" one...but it sure comes in handy when you don't have one.