Probably due to H.265 having much more expensive licensing costs than H.264, given enough volume. That alone might make lots of players in the industry to just prefer ignoring the new codec (and joining a joint effort for developing a new codec with more favorable licensing terms...)
Yeah, VP9 will probably monopolize the market as the libre, royalty free codec. With Google and others boosting it, I'd be surprised if it doesn't win like Opus has in the voice codec arena for any new application.
