Hi Nick,
Unfortunately, this turned into a religious war a long time ago and the primary consideration with regard to dhcpv6 has not been what's best for ipv6 or ipv6 users or ipv6 operators, but ensuring that dhcpv6 is sufficiently crippled as a protocol that it cannot be deployed without RA due to lack of features.
As a network operator what I'm afraid of is the exact opposite: DHCP duplicating everything that RA does so that I now have duplicate and possibly conflicting sources of information. I already have to put DNS resolvers in both because some operating systems only use the ones provided in the RA and others only use those from DHCP. I can'd even begin to imagine the mess if e.g. routing information is also duplicated, with different operating systems using different sources. I don't really care about the solution itself. I don't mind the original situation where routing stuff is done in RA and the rest is done in DHCP. I wouldn't have minded if everything was in RA, or everything was in DHCP. But the worst choice would be conflicting or overlapping solutions with some people religiously only implementing one of them. There are always trade-offs. And some stupid design decisions were made in the past. But let's not create an even bigger mess... Cheers, Sander