The sixteen megabyte limit you are referring to is just the default setting, this can be changed by anyone using Bitcoin Unlimited. We could even all agree on a two megabyte blocksize limit and then that would become the new consensus through using Bitcoin Unlimited. It is about giving everyone the freedom of choice, this was always possible before, Bitcoin Unlimited only makes it more convenient by having this implemented within the client itself and an easy to use GUI. The name Bitcoin Unlimited does not refer to an unlimited blocksize but it refers to the unlimited choice and freedom it unlocks.