[Dagger2]

That might well have been a more immediately pressing issue, but they did know that v4 was going to be too small and that they still needed to work on v6.

I might be saying something obvious here, but address space exhaustion and size of the core routing table are really two sides of the same problem anyway. The way to keep the routing table size down is to give everybody a small number of big allocations instead of a big number of small allocations, but that consumes more address space since the allocations have to be rounded up to at minimum the next integer power of 2 (and really more, to accommodate growth).