And... this is where it gets political
It's been political from the very beginning.
There was a (technically) perfectly adequate proposal on the table from the IAB based on existing standards that got shot down owing to NIH. That was more than 20 years go. At that point there was a greater diversity of networking technologies and a window of opporunity for them to converge on IPv6: instead, they converged on IPv4.
And a lot of the intervening time has been spent elaborating recommended ways of transitioning, many of which have since been deprecated.
Whatever their internal disagreements, the IP community have a Unix-like disdain of outsiders, so I wouldn't assume automatically that the ITU's ideas are necessarily any more fanciful than have at times emerged from those of the true faith.