Quoted from Deez:Why does routing a game lessen the value?
Because beating the crap out of a game effects it's condition which is the only real determining factor of it's value.
By beating the crap out of it I mean
leaving it on all day for kids to mash flippers/kick when ball drains
while dad spills a beer on it
and older brother carves initials in it
etc.
Those things are much more likely to happen on route rather then in a private gameroom.