IE7 was last updated over 3 years ago and doesn't even pass Acid2. Only 1.5% of internet users use IE7, and most of those are probably stuck there due to corporate governance rather than choice.
And yes, corporate governance regarding browsers does weigh in heavily in mass-market sites here, so we have to make sure the layouts don't break - Ink enables delivering a predictable, working layout that degrades gracefully down to IE7 for that reason.