It's a classic chicken and egg problem. IPv4 is still "good enough" as far as most people are concerned, so even with the squeeze on available addresses, there'

It's a classic chicken and egg problem. IPv4 is still "good enough" as far as most people are concerned, so even with the squeeze on available addresses, there's just not quite enough need to come over the inertial against supporting IPv6. Because of that, there's no demand driving adoption from any particular side: ISPs can get away with giving people IPv4 addresses only because IPv4 space is where all the content is, hosting providers have no great impetus so long as they're not seeing much IPv6 traffic[1], their customers know IPv4 and the benefits of all the additional address space are either too abstract or too scary ('Oh, my! That IP address is huge!'), and there's still enough legacy networking equipment, both professional and home, that only supports IPv4 that it can be hard to make a business case to get rid of. [1] Which is a pity, though not at all universal. The hosting company I work for takes pride in the fact that nearly our whole network, except for some colo boxes, some rapidly disappearing legacy boxes, and the like, is dual stack. Not all hosting providers think this way, and even when they do, they're customers often just ignore IPv6 because they know IPv4 and that's good enough for them. It doesn't help that an embarrassing number of ccTLD registries don't support IPv6 glue records.