The lack of Flash on Metro IE10 is a massive fail. I've just updated my original thread post with this and i'll just paste what i said there...
Apparently this is to help with security (even though HTML5 has more than enough security holes), but
apparently is also to help battery life. Even when HTML5 animations and video can often use MORE CPU usage than the equivalent thing done in Flash. And Flash's 10.2 Stage Video feature has the best in class video hardware acceleration. I know this for a fact as i've been developing with Flash for a decade and HTML5 for 2+ years.
You can always switch to the desktop and use any normal browser with plugins, but on a mobile touch device this isn't ideal.
As for Flash not supporting touch as NathanE said... wot?! Too much Apple koolaid? It's always supported touch, since the 90's! But like with ANYTHING it's up to the developer to actually make there site/game/app/whatever work well with touch. Some Android apps are actually Flash.
BTW the top selling game on Apples App Store at the moment (Machinarium) was made in Flash... how ironic is that? LOL.
Theres also still a ton of things that HTML5 cant do that Flash can. Flash also gets yearly updates so will always remain ahead (there was over a decade from HTML4 to HTML5 and it's
still not finished).
Flash Player 11 has access to DirectX and OpenGL enabling console level graphics (see below).
I actually think this is a big reason why MS are not allowing Flash on Metro IE.... why pay for a Metro App on the new store, when you can play a free Flash game with the level of graphics (or better) as in the below video. Anything DirextX graphics can do Flash can now do.