The switch from IE6 is a painful one, because they would have to apply it to every single computer in the company.
Depending on the number of exployees, that becomes a logistical nightmare.
Also, they will commonly use whatever browser comes with the default install of the OS they use for new computers.
Changing default programs introduces unknown risk, and the benefit of switching must outweigh that risk. Currently the hassle of attempting to upgrade every single computer probably outweighs the convenience of having a better browser, especially when most of the users will not take advantage of any of the new features.
