When you see v7 vs. V4, you'd expect the higher number to be better, hopefully better in all aspects, I wouldn't have expected such a thoughtful consideration to be required before upgrading. UUID-b would've been a better name then ;)

that is pretty common with uuid. for example in many cases you'll still want a plain uuid4 instead of e.g.uuid 5. maybe you want 5. it's usecase dependent.

for a specification such as uuid, there is not much to improve upon--just rearranging the bytes and their meanings.