Simply everyone loves 'Open Web Standards' without any limit and HTML5 reaches that milestone without much competition, even flash is gradually disappearing.
HTML5 is going way beyond the browsers, you can make desktop apps too without learning the other complicated eco-systems.
The next important market is mobile apps where again HTML5 leads the number, now more and more companies backing up standards which is good for all, nonetheless so much to see in the future of web standards.
