I think it's a mistake to specify 'IT department'. Just as IT departments often don't have usability as a primary concern, the corporation itself often doesn't

I think it's a mistake to specify 'IT department'. Just as IT departments often don't have usability as a primary concern, the corporation itself often doesn't have technical fitness as a concern. To them, almost all technology decisions are dominated by the concern of corporate risk. They want industry-standards, because it keeps cog replacement costs down. They want you to use their gear to minimize data security concerns. They want to shut down youtube, lest they appear to be not enforcing the harassment policy. They force IE6 because they're trying to meet return projections on bad investments from years ago. They provide a standardized environment so they can shuffle cogs more easily. Etc. Even if the average user always chose the best available tool, even if they were security-conscious, studiously making regular backups and vigilantly updating their software - corporate concerns would still regularly trump their desire to have X. Just pick an IT guy and ask him how much say he has in what software he has to use all day.