IPv6 added more digits, maybe too many... But it also fixed some weirdness of IPv4. Mostly being sensible upgrades aiming for less manually configured networks.

IPv6 added more digits, maybe too many... But it also fixed some weirdness of IPv4. Mostly being sensible upgrades aiming for less manually configured networks. Adding more digits sounds simple, but there is no good room in IPv4 packet. And then any solution using existing one would not anyways be backwards compatible. So for each round of new byte you add to header you would have different version anyway. Requiring new hardware and software.