You don't "need" them, but they're almost universally understood and supported which makes them super convenient and a good starting point for many use cases.

You don't "need" them, but they're almost universally understood and supported which makes them super convenient and a good starting point for many use cases. The point in which the "wasteful" nature of a UUUID really bites you is so far down the road that it is almost not even worth thinking about until you get there. Chances are you won't be dealing in petabytes at all and the 64 bit savings you are fretting over doesn't really matter.