Advantages of IPv4 over IPv6

Solution 1:

1. Simpler
   1. IPs a normal human might be able to remember.
   2. Less programming, less memory, etc.
2. Familiarity
   1. Thousands (millions?) of Network and System Administrators already know it.
   2. Existing infrastructure supports it at almost every level already.

Solution 2:

Legacy support is the only one I can think of. It's been implemented and re-implemented to the point that just about everything out there would support it properly so lowest-common-denominator cheap equipment shouldn't, in theory, screw it up.

IPv6 is compatible with IPv4 but it's not widespread enough to the masses to show bugs in implementations yet, in my opinion. I'm sure someone's Internet enabled doodad will bug out because of an issue with interacting on IPv6.

Solution 3:

• It's easier to read and remember.
• Better supported