I was just checking out a great little HTML5 and CSS3 checklist by findmebyip.com. They've looked at the top five browsers, both PC and Mac, and looked at whether it supported CSS3 Properties, CSS3 Selectors, HTML5 Web Applications, HTML5 Embedded Content, HTML5 Audio Codecs, HTML5 Video Codecs, HTML5 Forms Inputs and HTML5 Forms Attributes.
I make my living in this world. Web-based work pays my mortgage and feeds my kids. This matters to me.
You don't have to know a stitch about HTML5 or CSS3 to see in this chart that IE6, IE7 and IE8 fare very poorly. This begs the question: if IE ignores it, does it exist?
And yes, I'm being serious. We don't develop web sites for ourselves or our web-savvy brethren, we do it for the masses, and that means we do it for IE.
How much time and energy would you commit to something that couldn't be seen or appreciated in Internet Explorer?