How thin is too thin?

I have been in several disaster planning sessions recently in which it has been stressed that you need to define who your "key personnel" are in the event of an emergency. I began to think about how organizations have thinned themselves down over the recent years in the name of "doing more with less" or "being lean and mean." At current staffing levels, you have to wonder who is not key personnel?
The fact of the matter is, we have trimmed most of the human redundancy out of our organizations. Don't think so? How many times have you been told that something can't be done because a particular individual is sick or on vacation? If a job function cannot be performed because someone is gone, then perhaps we have trimmed too far.
Now before the words "cross-training" spill out of your mouth, keep in mind that many (should I say most?) of us have enough of our own work to do without having to take on someone else's work as well in the event that they are out. Now I am not against being a team player, and certainly cross- training is an important concept in the work place. But often these concepts are used as an excuse for not hiring needed people.
This wave of staff thinning in order to stay competitive can and will show itself to be extremely self- defeating during an epidemic or pandemic. Should the worst-case predictions come true, many of our "key" personnel won't be around to depend on - and there are few backups to be found. Compound this with our "just in time" economy and you can imagine the dire consequences.
This is particularly true in the IT area where staff has been thinned to the point that preventive maintenance is wishful thinking and "proactive" is a thing of the past. "Reactive" is the operative word because there are not enough people to go around to do all that needs to be done. Something has to give, and that something tends to be preventive maintenance and customer service.
This is a particular problem for most organizations who see technology and IT as their way of surviving in disaster/pandemic situations. Data centers work in "lights out" mode for only so long before something needs human attention. Where will the humans be to remedy the situation? The same goes for outsourcing. If a pandemic truly hits the world, do you think any service level agreements with a company in another country are going to be worth the paper it is written on?
My point to all of this is that increased staffing (and funding) makes us better prepared to withstand adversity, just as a few pounds of extra fat can mean the difference between life and death for a sick person. Given that pandemic flu planning is becoming more and more prevalent, I think this is a perfect opportunity to make the case that additional staff and funding are not only appropriate but necessary to be truly prepared for such a disaster.
Lastly, please understand that there is a difference between "adequately staffed" and "bureaucracy." I'm not championing for the times where organizations had so many people that they created layers of work for people to do to justify their employment. I just believe there is a happy medium between fat and thin, and most of us are way too far on the lean side. I also believe that this leanness has reached the point where it is bad for business and has left us vulnerable. We live in a society that is far more dependent on others than the last society that had to deal with an epidemic/pandemic. Despite our advances in medicine and technology, I believe we are more fragile as organizations and societies. I think it is well past time that we do some fattening up. Now if we could only get those that control the purse strings to listen.