Who are "they"? I imagine the overlap between people working on the core python language and people maintaining popular third party libraries is pretty small. Or are you suggesting that Van Rossum and friends drop python development for a year and start hacking on NLTK and PIL instead?
1. Because it's not really their job, the core team ports their own libraries and (as far as I know) are always available to help others do so for theirs.
2. Because some of the Python 3.2 fixes and improvements are needed for library migrations.
Have you read PEP 3003? Python 3 is hardly moving forward.
I think it would benefit you to read the PEP before making such a post.
I have read it, but evidently I'm misunderstanding something, either in the parent post or the PEP. Would you care to be a bit more explicit in pointing it out?