Back before Firefox became popular, Network World polled a number of CIOs regarding browsers. The consensus was they'd like to get people off IE for security reasons (and this was three years or so ago!), but so many of them had too much invested in ActiveX intranet apps - which pretty much meant they were stuck with IE for in-house use.
Since Microsoft had this de facto browser monopoly already, they dragged their feet with regard to implementing newer web standards and more complete CSS and DOM support. You can't really blame them for that, IMHO - why would anyone expect them to act against their own corporate best interest?
In spite of this handicap Firefox managed to eventually take off (home use driving work adoption, I'm guessing), and so Microsoft has been much more about web standards with IE 8 and 9. Plus MS is being much more forthright about the fundamental security problems ActiveX introduces. But given how easy it is to make ActiveX apps (it really is a trained monkey sort of thing - and MS provided free or cheap training to a lot of monkeys), I don't think it's surprising that a significant number of companies still resist moving into the 21st century. It's not that hard to make modern web apps, but I've known a number of these ActiveX monkeys and they're just not that good.