The problem is a standard can be 'open' yet restricted, i.e. you have to pay to distribute software using it. Can't pay? Can't give people the program. The tricks that LAME uses to work around MP3 encoding patents aren't going to work for browsers.

Of course it will go away once the patents expire, just like with GIF, but calling it 'open' now is just marketing speak which doesn't come close to the actual nature and purpose of open-source software.