Well, there's a couple other considerations. For one thing, some devices may have multiple IPv6 addresses - perhaps even entire slices of it. For another, having additional bits to work with allows people more room to divide their subnets into future-proof chunks without risking ever running out of IPv6 space - something IPv4 could never really afford in the first place. What would be considered large chunks of IPv4 are a drop in the bucket in IPv6.
I think the main idea is that you want to have plenty of space both for growing horizontally and vertically, at least enough to where you can't even imagine exhausting it in either direction. Giving massive private and public address space without need for NATs effectively provides this.
Also, hey, who knows. There isn't enough raw materials on Earth, perhaps, but maybe there are enough raw materials in the universe. Who knows for sure if the Internet always be confined to just Earth.
Unless you get faster than light communication, the interplanetary protocols will require advanced collision handling which TCP does not provide anyway, and all kinds of "on-line" access will be impossible due to light lag.
I think the main idea is that you want to have plenty of space both for growing horizontally and vertically, at least enough to where you can't even imagine exhausting it in either direction. Giving massive private and public address space without need for NATs effectively provides this.
Also, hey, who knows. There isn't enough raw materials on Earth, perhaps, but maybe there are enough raw materials in the universe. Who knows for sure if the Internet always be confined to just Earth.