Good point!
I have big rubber floor mats on top of my rubber mat and only put the tire dressing on the center hump, the sides get a little shine from the overspray but aren't taking a direct hit.

the center hump does seem a little slimey. I don't know if it would fall into the slippery catagory but I'm sure it easily could with the right footwear.

But you're right it's kinda like suggesting somebody Armor All a motorcycle seat "because it looks good"