I know a lot of endsites, that (essentially) have (a) a lot more need for address space than many ISPs and (b) the realistic chance to deploy IPv6 in a large network, because they can actually force the use of IPv6 in their network.
Note: end sites can get _lots_ of address space from their ISP. The issue is not about getting address space, it's whether address space is obtained direct from an RIR (with the presumption that it will be PI) or from the ISP. We simply do not know how to scale routing within the network if we give every end site its own direct allocation. Given that we don't know how to do it, it's _really_ hard to come up with fair/scalable policies that give only _some_ (e.g., the "biggest", however you define that) end sites a direct allocation, but not others.
I think this fight for "Allocations of Address space only to ISPs" is one of the best reasons not to do IPv6. Actually the only reason for this rule that I can think of is, that it is made by ISPs who as it seems either believe they have the biggest networks or believe they could tie up customers with that. I think both assumptions are plain wrong.
No. The reason for this rule is fundamentally a technical one. We do not know how to give every end site a direct allocation and keep the routing system afloat. This is a _real_ technical issue, and is not just something the ISPs have dreamed up to capture customers. (Well, some ISPs may welcome this as a side-effect, but it is not the real motivation for the policy). Thomas