Please note that Ryan’s “manage their IPv6 systems” really means “run their business”. In many organizations the routing network is managed by a different group with different business goals and procedures than end systems. Allowing flexibility for this, if it is not overwhelmingly costly, is a reasonable goal.
I guess in that case, one must ask one's self whether setting the default (or any other) route entries in the host routing tables qualifies as a "end system" issue or a "routing network" issue. My inclination is to think that it really is a "routing network" issue more than a "end system" issue, but I can see some valid arguments in either direction. It seems to me that no matter what solution one uses to deliver the default route information to the end system's routing table, this is an area which will inherently require cooperation and interaction between the group that manages the end systems and the group that manages the routers. I have yet to see an environment where this can be avoided in IPv4 and I wouldn't expect it to work out particularly well in IPv6, though I think we can come closer to having it work by having the network group control the prefix assignment and routing information delivered to the hosts than we could otherwise.
On my part, I see adding a default route parameter to DHCPv6 about as earth shaking as adding a default NTP server list. In other words, cut the crap and do it so we can save NANOG electrons and get on with solving more important network problems.
Personally, I'd hate to see us waste the effort on such a half-assed measure. If we're going to add routing information to DHCPv6, then I think it should be roughly equivalent to what is contained in an RIO within an RA (Prefix, Mask, Next Hop, Metric). (Though in the case of RA, the Next Hop is implicitly the router providing the RIO, obviously in DHCPv6, it would have to be explicit) With such an option added to DHCPv6, then default router could simply be one case, but the flexibility for more complex routing situations to be addressed would also exist. Owen