Companies seem to think that the IT dept is the most expendable for some reason.
You say this as if it is a mystery why a company would feel this way. But regardless of whether IT is as expendable as some companies may treat it, I think it is important to understand why things are the way they are.
To any large company, there are essentially two parts. First, there is the part of the company devoted to whatever the company sells. This will include engineering and design, product, sales and marketing, and perhaps some portion of management.
On there other side, there is the part of the company that is there so that the company runs smoothly. This is the part of the company that is there to facilitate and support the first part of the company. IT is in this group (in a non-IT company), as are janitorial staff, a certain other amount of management, and other random departments which might vary from company to company.
There is, of course, some overlap between the two sides. For example, while you might consider the running of the website an IT role, it is also essential to sales. Still, viewing a company as having the two sides is helpful for understanding why companies see IT the way they do.
When money is tight, and a person needs to decide where to cut money, they cut the things they deem less important to their survival. They can refuse to buy a new stereo or new underwear, but they can't refuse to buy any more food.
Similarly, when money is tight and a company needs to decide what to cut, they get rid of what they deem to be the least important to their survival. From upper management's point of view, they see what the impact of laying off staff in their core business will be, and will be less likely to view management as just support. However, it is harder for them to see why they can't just halve their IT staff or janitorial staff. Maybe the floors will get vacuumed less often or it will take slightly longer to deploy Windows 7, but the company will still do what it does roughly as well as it currently does, right? (That is not to say that IT isn't crucial to a company's success, just that it is much harder for upper management to appreciate the relative worth of IT staff).
It's much harder to appreciate exactly how expendable support staff is, but it isn't that hard to see why management would view support staff as more expendable than others.