Rubber items will eventually degrade and split with UV exposure and general wear and tear.
Anti vibration parts like this perform a vital function in protecting against damaging vibration. Renewing this item will be less expensive than replacing the Fuel Tank because of high frequency vibration damage!
If the Fuel Tank is to be removed and replaced then renewing this item would be a sensible move. Make sure you order all the parts required at the same time and save money by avoiding multiple shipping costs!