Back in 2003 I was testing Cisco's hardware (as much as the IPv4 version is) IPv6 multicast snooping and routing. We were playing different full-rate video streams over a large multi-site IP network with maybe a dozen switch clusters. Without multicast, this was a quagmire (each person viewing incrementally increases the bandwidth needed at pinch points, until performance becomes excruciating) and without IPv6 it requires lots of management because the (Class D in this case) addresses were scarce and must be handled very carefully. With both it was a joy.
Granted, we found several nasty bugs and spent long evenings on transatlantic telephone calls getting their engineers to reproduce them. But that was now almost EIGHT YEARS AGO. This stuff was available for production users when ISPs were buying the gear that's now dusty and old and being thrown out. But they didn't buy it, because less capable gear is always cheaper.
In some way it's our fault as consumers. Most ISPs live on razor thin margins. If everybody was happily paying 50% more for Internet access there'd be money to buy anything the ISP's engineers could want, have real coffee in the DC quiet area, and still buy the Chairman a yacht. But it's a cut-throat business, only specialist players can afford to charge more and deliver better service.