I would imagine the main reason for changing the case design is to keep from having to pay any type of royalties on using the traditional .308 nato round and just isntalling a flat tip bullet into it.
By putting a flat tip bullet in it you would not gain anything. They designed it to take advantage of the new Hornady Leverevolution bullets. Also the case is changed to keep people from shooting regular .308 rounds in it and having the shells go off because of the pointed bullets so it is a safety factor. That is the same reason they put a rim on the .450 Marlin to keep people from using it in older .45/70 rifles and having them blow up.