[retrac]

I've seen some people express reservation by how greedily they're allocating IPv6 blocks. Will home network /64 prefixes one day be like how Ford Motor Company owns all of 19.0.0.0 in IPv4? Well, probably not. But there's already a lot fewer than 128 bits of real addresses to hand out.

[kmeisthax]

/64 is the smallest available subnet by design and many things will break the moment you try to subdivide further. The idea was that the lower 64 bits would identify a particular NIC by it's MAC address; this was later changed to be a randomized suffix. This is why most machines typically have hundreds of v6 addresses - they generate a new one every few hours.