The pressurized basket ensures you get crema from any beans, any grind and any tamp. It doesnt ensure a decent cup :(
The plastic thing does nothing except gather crud underneath where you cant see it but where it can and does affect the taste of the coffee >:(
Definitely take it out.
I recommend you sign up for the free Sunbeam training course which is machine specific. You will learn how to get the best out of your setup. They will be using the Sunbeam EM0480 grinder - is that what you are using?