I like to think that Goofy represents the "comfort zone."
Yes, Goofy doesn't fight, but on an important mission, he'll be there at Darkwing Tower, ready to help heal anyone injured, or prepare any materials they need (after tripping over several things in the process^^')
I even like to think that it would be Goofy who would take care of Tim (and in the future Audrey and Olivia), so that Gosalyn, Max and the rest of the team can fight without worries.
And the truth is, knowing that you have Goofy there waiting for you after a hard fight is really a nice feeling, isn't it^^?