Per-connection MTU's are a pain. You shouldn't be making that point if you think that routers having a PNAT table is a hack - having state is awful. And IPv6 has other flaws too: some headers fields are unprotected from bit-errors in transit. There is no specification as to how many extension headers I'm allowed to use. Higher layer fragments are completely unrecognisable to stateless concentrators (more so than in IPv4). UDP- and TCP-checksums are not allowed to be all zeroes (which was neat when you provided a better checksum yourself over, you know, fragments, which got ripped out).
No there's plenty rotten in the state of IPv6. And it's not just because 'interests' ripped things out.