> I think they are not afraid, they just see 0 reasons to
This is a big part of it. Apart from extra addresses, it offers remarkably little benefit in terms of networking features from an operational management perspective. It sounds like it should be better when you look at the features, but, in actual operation the features don't really offer that much.
Further, there's the general problem that for some reason the network equipment manufacturers seem to think that because you don't frequently need NAT that now you don't need to have a stateful firewall just always on by default on a network edge device.
Plus the general confusion among tech neophytes that NAT itself is offering actual security features, so that a stateful firewall is a downgrade. This is such a fundamental misunderstanding that you can't even communicate with a person that believes it to be the case. I fear that this confusion will remain with us for decades. I'm sure me even mentioning it will spawn a whole thread of people vehemently disagreeing, because there is always at least one.
This is coupled with the fact that the addresses are just ugly. Like, I'm sorry, but unless you're exactly an electrical engineer, the IPv6 addressing scheme is difficult to remember. IPv4 has the same problem -- the magic numbers are only easy to remember if you have memorized the binary values, too -- but it's really only a handful of things to remember in comparison. Hex values are just not as easy to read or remember compared to decimal numbers. So even though IPv6 isn't harder to use, it feels like it's much harder to use.