Does it really NEED it? No, not really... I'm sort of obsessive about audio stuff, though, and the car is fairly loud. I'm not sure how crazy I'm going to get with the stuff. I may just do the doors, which should improve my midbass response quite a bit.
But, you're right, the stuff is really heavy.
I guess the other reason that I want to do it is because it's a project where I get to take apart my car.
Adam