There are a number of good and reasonable uses for RFC1918 addresses. Just assume a individual/business/corporate LAN with client/server applications and statically configured ip numbering. RFC1918 addresses are perfect. NAT allows this network to be connected through any provider(s) to the Internet. There is no risk of collision of the internal address with publically routed addresses.
To do without RFC1918 type address space it expect to
a. Obtain unique, permanent address space for personal/business/corporate use b. Receive this unique, permanent address space at no cost c. Have this unique address space routed via any provider of my choosing
I see this a lot recently: You are mixing up RfC1918 and NAT.
If I have globally unique addresses I can NAT them as well as 10/8. One has nothing to do with the other.
Having to NAT RfC1918 addresses to reach the internet, does not imply that I have to have RfC1918 to be able to do NAT.
What are my options today to obtain ip address space? My requirements are well met by a /27 subnet. ARIN won't give me a globally unique /27 for personal use. So the /27 comes from my service provider, which has several caveats. I cannot multi-home. I cannot keep my address space when changing providers. I most likely cannot keep my address space moving to a different city but staying with the same provider. About half of the devices within my on private network are statically defined and for local use only. They will never need global access. Because they are awkward to configure I do not want to renumber, ever. My solution is to use RFC1918 address space for this network. RFC1918 address space is free and plentiful for my purposes. It is provider independent. It is globally unique in the sense that no other publically routed network is using them. My globally unique address will come from my provider of the day. NAT is my technology of choice to connect to the global internet, but other solutions are possible. If I understand correctly, ipv6 will force me into using provider dependent globally unique address space. Unless my provider of the day is required to assign me address space that is and/or permanently assigned and portable it does not meet my needs. Why not? I am not willing to renumber when I change providers. I have no problem using NAT to obtain connectivity from provider B using providers A address space internally. But that only works if provider A is prevented from reusing 'my' addresses if I terminate my contract. And what do I do if I build my network without ties to any provider? Can I go to ARIN to get globally unique address space, an ipv6 /48? Without RFC1918 that would be my only choice to prevent from overlapping my network with someone elses. If you're telling me that I can get provider independent globally routable address space for a small network at a reasonable cost I'd jump for joy and never look at RFC1918 again. But I don't see that offered as an option, so an RFC1918 block in ipv6 makes all the sense in the world to me. Adi