Comment by throw0101a

> It is a common misunderstanding (I hear “we could have just made IPv4 bigger” a lot) but apart from the routing issues above (needing to replace every router before it could work at all), the endpoints are also a problem.

Don't forget all the DNS software: "A" records are hard-coded to 32-bits, so if you wanted >32 you needed a record type (what we now call "AAAA", RFC 3596).

Then all the DNS programming APIs had to be updated and all the C header files with new structs.