Hi Chris!
Is it necessary to put floor mats in your car? Of course not, but they are comfortable and protect the carpets. The car will go with or without them.
Like the floor mats, cork roadbed cushions the track, enhances the appearance, and, in my opinion, keeps the track cleaner and easier to maintain, but it is not necessary. Many modelers prefer to simply paint the roadbed, which was what you will see in the classic Lionel display layouts.