Black foam padding under fuel tank??

I fitted the Ducati performance air-filter/air-box lid set to my 620 last night and obviously had to lift up the tank (first time I have done it), underneath the tank was a black foam padding ‘jacket’, presumably it filled the gap between the tank and the old air-box lid.

I didn’t see that it was doing much and because the new air-box lid is now completely open I’ve taken the padding out.

What is the padding for?

And was I correct to take it out? (I can easily put it back in)

Thanks, Mark.