The thing is we could do wonderful stuff on webpages, mind boggling stuff. Think 3D world, think music visualization, think games. That and much, much more.
But, we can't because MSIE is holding us back. We can't make use of the speed other browsers are offering while MSIE still exists.
The other thing is that developing MSIE compatibility costs a lot of time & money. Money we don't get from Microsoft, so we have to charge the customers for it. That and it's really quite frustrating to develop a program for 2 hours, then spend 20 getting it to work in MSIE (no, I'm not exaggerating).