I think the "seasoning" is a good thing in general, you want it on the inside walls and door of the smoker but not really on the bottom, or on the racks and rack rails, chip box, etc. A good degreaser or oven cleaner should take care of this. I really think he should update his seasoning instructions to warn owners not to season the entire insides of the smoker. It's not really obvious to new users.
An alternative to using foil to line the bottom might be using one of those Kevlar oven liners. They're cheap and you can cut one down to size to fit the bottom of your smoker perfectly. Grease and crap doesn't stick to them so they wipe clean with a damp cloth and last a lifetime. You'd still need a small piece of foil to cover the top of the chip box.
I think the smoker should be cleaned regularly. I scrub mine out with hot soap and water after each use, it removes the grease and food scraps but leaves the seasoning intact.
mike...