most use just three or four features out of that list. And IE10 is adding support for many of them. By leaving them out you're hurting users for no reason.

    drop IE6: great! kill it with fire
    drop IE7: reasonable
    drop IE8: risky, millions of users
    drop IE9: kind of stupid. 15% of the web, soon to be 30%

So much for fighting for open standards.