I’ve generally considered IPv6 neighbor discovery to be a worse hack than ARP. ARP is a straightforward, fairly clean hack to layer the IPv4 addressing scheme over Ethernet, and it doesn’t pollute IPv4 itself. Neighbor discovery layers IPv6 on top of pseudo-IPv6, where the latter operates without knowledge of MAC addresses but nonetheless hardcodes knowledge of Ethernet. But hey, it eliminated the use of Ethernet broadcast in favor of a more complex but functionally identical multicast scheme.
Oh sure, the point is more that Ethernet/IP has to coordinate two separate ID spaces at all, whereas AFAIK no other packet-based protocol like the ones mentioned does this, so in that sense those protocols are better.
