I think you're right that at least a certain segment of the population no longer thinks animal stories or anthropomorphics are merely childish things. But those who do think this continue to run the show in many cases. Bookstores and libraries will insist on placing these titles in the children's section, even when they are utterly inappropriate there.

And need I even mention the attitudes of many toward furry fandom?

Kenneth Grahame is up next, and he's the man I give credit to for making anthropomorphic stories at least somewhat acceptable to adult readers. ;)