I've always been told that all Pearl parts.....right down to the smallest screw. nut, or (I assume) FF cradle felt, can indeed be bought. It may take some internet sleuthing to obtain the correct part number. It may also take some time for your local Pearl dealer to order one for you, making the whole exercise far more effort than it is worth. But it's certainly my understanding that all Pearl parts.....no matter how big, or small.....are available to be purchased after market.
As to whether or not it's necessary. If it were me, I'd try the shell without the felt and determine for myself whether or not I thought it was worth the effort pursuing it.