Remember, these fancy computing devices were built for the rich and the government, not for the average joe, noone thought computing would be this easily accessible.
NAT is a colossal pain in the ass. I shudder to think of the number of man-years that have been spent on NAT traversal. NAT breaks one of the fundamental functions of an IP address - a unique identifier for a network device. It turns a simple identifier into a weird, amorphous abstraction.
IPv6 isn't perfect, but we could have avoided a lot of hassle if we'd started off with it.
Sharding, or a second key, or detecting the iPad and using a lower number with an offset internally? Still requires special handling at one end or another.
Remember, these fancy computing devices were built for the rich and the government, not for the average joe, noone thought computing would be this easily accessible.