One problem with the modern system is that it seems to be an unstable equilibrium - it's more efficient, but what happens if the global logistics infrastructure breaks down because of war/rising oil prices/political turmoil etc? It seems that we (meaning communities/regions/the US) have given up self-sufficiency in exchange for this increased efficiency, which surely has some sort of cost.
What happens if some local infrastructure breaks down in a way that that the local community is put to a standstill until things get fixed?
A good example of this: a major highway bridge becomes impassible in a way that is not trivial to repair. The lack of this bridge becomes a huge expense and drain on quality of life in the region. You can either ride of self-sufficiency to get this bridge rebuilt, or you can rely on the efficiencies of volume producers of raw materials, machinery, and whatever else you'll need to build that bridge back up.
Self-sufficiency, in the sense that you exchange with few or no other people for your own wants and needs has huge costs as well; but, because most of us aren't self-sufficient in that sense, we tend to romantically gaze in that direction and only remember all the good that comes out of being self-sufficient. The trade-offs are not that obvious and one-sided.
In a non-networked world, the problem is limited to the local community. In a networked world, everyone is harmed.
It's pretty easy to see that there are tradeoffs to be made between reliability and efficiency. As we become dependent on products which are centrally produced (very efficiently) and widely distributed, we all become vulnerable when a disaster strikes the producers.
I personally believe that the efficiency gains outweigh the reliability losses, but that doesn't mean the tradeoffs don't exist.
True, and I tend to underestimate just how centralized the production of a lot of things are, since what I do isn't really based that heavily on geographic location.
My counter to that, though, is that there is usually at least a couple of producers of most products, and that sometimes -- though not always -- they are geographically separated enough that the risk is somewhat mitigated. Other times, though, geographic constraints sort of mandate that every supplier be located within a small number of miles of one another; suppliers of natural resources (coal, oil, etc) come immediately to mind.