The feature is also present in other large aircraft and widebodies as well. The 787 had a notable incident last year where the valve was left open and caused fuel to be vented drawing unwanted attention from the media at a time when it was plagued with other problems... edition.cnn.com/2013/01/08/travel/dreamliner-fuel-leak/
As for active fuel dumping, it is an additional feature for large aircraft since they tank more fuel and need to reduce a lot of fuel weight for emergency landings. Not all may have it though. For instance, the fuel dump system is a customer option on the A330 depending on their requirements.