Apple and MS don't like legal uncertainty and additional risks in choosing technologies. Open never entered into it. People also forget some of the problem both companies had with MPEG-LA.
> H.264 has a group of companies and a lot of lawyers backing it up.
How can it help against some patent troll who can appear tomorrow and threaten H.264 users? No army of lawyers can help against that. So all this rhetoric is completely useless. Legally VP8 is as good as H.264. The only reason for them to avoid is to retain their monopolistic grip on codecs usage.