% As John Klensin pointed out on this same list several weeks ago
% (and I'm sure he said it better than I will), the decision to
% use ambiguous local addressing in IPv4 (i.e. RFC 1918 addresses)
% was partially motivated by the desire to conserve IPv4 address
% space. In IPv6, we don't have an address space shortage, so there
% is no reason to introduce architectural complexity to conserve
% address space.
"dont' have an address space shortage..." - Margaret
IPv4 didn't have one either, in its early days.
Opinions expressed may not even be mine by the time you read them, and
certainly don't reflect those of any other entity (legal or otherwise).