There is a similar piece of clear plastic about 3' X 3" affixed to the top of the rear bumper. I asked the salesman what it was for, and was told it was to protect the bumper from getting scratched when people rested their grocery sacks on it. That little strip of clear protective plastic costs $75.

 

I ended up buying that part from Sewellparts online ($40 I think) - and just installed it myself.
Is the material really worth $40? Not at all ($10 at most. I think they charge the extra $30 for the Lexus Logo! lol!). But it does protect the top of the bumper pretty well.

 

I have them also. Mine clean up easily.

 

Ditto. Same for the film the dealer put on the top of my bumper where the trunk opens to keep the bumper from getting scratched when loading things. I just try to stay away from those areas while waxing. The wax residue will turn dark in there over time unless it is removed.

 

for whatever reason it may be, it's an eye sore to me...

it looks like an aftermarket tool for those who has scratch on the car, not for a car that is clean and scratch free...