This is one of the first cars I've seen where that plastic is an integral part of the design (vs an add-on), but I was just thrilled to see it because that plastic protects the part of the car that ALWAYS rusts first. Its a rust and corrosion preventative and its more than welcome on my car. You are the first person I've heard of to take issue with it, I think its pretty stylish.
There are more than enough places where they cut corners and costs on this car (you are going to start discovering those soon enough once you get yours, something for you to look forward to), I'm happy that this is not an area where they cheaped out because I have to drive through lots of road salt and brine with can eat through a rocker or fender lip in as little as two years around here.
If you traded in a first-gen Compass you should realize that the 2nd-gen is a whole new car, you are not getting a product that is anything like your old car (and the consensus here is that fact is a good thing).