Like has been said, the small saw blade on a SAK is not really appreciated until you have a use for it. It's so small that it adds very little bulk to the tool, but if it's needed, it's really needed and nothing else will do as well. It's always there in the pocket, like the rest of the small tools on a SAK or scout knife, so you won't be standing there with that "I wish I had a screw driver/saw/whatever" look on your face.
Small tools on pocket knives are like derringers. Not everyone wanted or needed to be walking around with three pounds of hogleg on their hip, but a small pistol in the pocket would do in a pinch. When you need it, you tend to be in circumstances that you need to right now. I can remember whittling down a few saplings on a cold snowy morning to make a litter to carry out a friends wife, when she slipped on some ice on an early morning hike. A SAK saw would have been very nice to have.
Never under estimate a pocket size tool in a pinch.