Nuances matter, and being cautious in respect to change is not the same (at all) as being afraid of it. I love Python and don't mind refactoring code from time to time if I perceive a benefit from doing it.
I think the "conservative" feeling comes from the fact that there's no immediate need to rush into Python3. Many changes were backported to version 2 and it has been a useful and dependable language for many years. So we have a good situation in which we can take our time to refactor the code and make the final transition when we feel it's ready.
On the other hand, the OP conflates changes in the language with changes in the applications built with it, which is an error. The Python community is very happy using the language in projects with cutting edge features and uses. You have to look further than just Django, at Scipy or Biopython in order to see that. In that respect the community is more eager of change than the one surrounding Ruby, which is mainly oriented to web development.
