It did matter. They were putting something in place that was going to cause problems and hold back development / progress for years to come.
MS could get away with that attitude 10 years ago with a 90% market share – an antisocial approach towards open standards was only a problem for *everyone else*.
With the benefit of hindsight we can see how destructive Microsoft's antisocial attitude has been, and yet they still continue to drag their feet with regards to CSS3 and open standards. IE will be dragged kicking and screaming through every major change for ever. Today we talk about wanting IE6x dead, and in 10 years we'll be talking about wanting IE7, 8 and 9 dead too.
The Chrome Frame goes a little way to making the lives of IE6x users that are stuck for the time being with an ugly dinosaur, a little easier. I like that.