Seems to me that alert() is to UX what document.write is to DOM manipulation.
— Shane (@freshclickmedia) May 23, 2012
Microsoft IE lead Dean Hachamovitch:
Running Metro style IE plug-in free improves battery life as well as security, reliability, and privacy for consumers. Plug-ins were important early on in the web’s history. But the web has come a long way since then with HTML5. Providing compatibility with legacy plug-in technologies would detract from, rather than improve, the consumer experience of browsing in the Metro style UI.
No Flash then.