Even Google, champion of HTML5, still forces the Flash player on YouTube for videos that have ads, regardless of what your browser supports (or doesn't). So immediately caving on h.264 wouldn't have gotten rid of Flash; it would've left the Web depending on one more not-quite-freely-implementable blob.
If nothing else, it's probably due in part to Mozilla's stance against h.264 that we're even having conversations about alternative codecs today.
If nothing else, it's probably due in part to Mozilla's stance against h.264 that we're even having conversations about alternative codecs today.