Over 20% of people still use IE. In some places, there is no choice. For my workplace, it is mandatory to use IE. Because I'm in IT I can get around some of these problems as I have admin rights to my box, but IE is still the official browser. Many of our in-house applications are built around IE quirks. This is because IE is officially supported by Microsoft, as with other browsers if we were to build around them and then they changed, we'd have no recourse.
The amount of users still using IE continues to fall so switching browsers could be fine. However, IE's default is still to display text from left to right unless instructed differently. So there must be a stylesheet/inline style/javascript/block container attribute at work here. My guess is there is a "center" at a high level, and then a style sheet applied so that elements lower on the tree get left aligned, and IE is missing the interpretation of these.