Plastic oil pans aren't that bad as long as you have a proper undertray. Had one in my C-class when I still had money to drive a nice car. It's just weight savings because of emissions regulations.

I'm much less fond of plastic valve covers in most modern engines, those tend to start leaking much faster, I've got a car with only 415k km that already has a leak from the plastic valve cover. Not an issue I've had with metal ones usually.