Yes, reverse thrust is just an added bonus. Isn't required at all. Some airplanes don't even have them (Bae146/Avro, Diamond Jet, CitationJets [had to put that in for you Jason] to name a few). Sometimes 1 or both reversers can be deferred. And some airlines/airports have agreements that only idle reverse thrust will be used (LHR if I remember requires it?).
On some performance calculations in the books for airplanes, reverse thrust isn't included. So it is just a greater stopping power. Depending on the airplane, outside conditions, runway conditions, and weight, reverse thrust sometimes doesn't do a whole lot for you.