Immagine a world where every framework / API / database had its own incompatible UUID format. Without a standard specification that's where we would end up. Do you want to live in such a world?
As long as they gave sufficient randomness etc, from a program perspective they are unique id's.
There are already multiple versions in active use (4, 7 and arguably 8) so you really shouldn't be using the uuid as anything but a long-random-value.
Yes, the database engine may appreciate one version over another for performance reasons, but that's irrelevant to most developers and programs.
Want visually recognizable unique identifiers?
JAGRSW-UID-<192bit-input-from-urandom-encoded-in-base64>
JUID-<192bit-input-from-urandom-encoded-in-base64>
Seriously, these UUID debates are about as sensible as arguing over XML.