I'm much happier to see it as a liability issue than one of customer ineptitude. Really, I shouldn't even suggest that it is "inept" or "moronic" if someone can't put their knife back together - different folks have different skills. Now, suing over a problem they caused themsleves... that's moronic.
The way I see it, Spyderco already has a number of people devoted to free-of-charge tasks like sharpening and repair, and re-assembly would only be another such task. Why would Spyderco offer this? For the same reason they offer other free work - it gets them buyer loyalty and the best reputation in the industry, and the money comes back in increased sales. I do think that re-assembly would be a very small workload if knives had proper illustrated manuals printed on a little slip of paper and packaged with each one. I remember how scary it was to pop open a Benchmade for the first time and not know what I would find! Maybe I was lucky, but this should be simple task for most folks with proper instructions
The other question is how to keep Spyderco from being liable for those folks who don't do it right... that's a bit trickier, but as you mentioned, there is precedent in other industries.
I've been watching the Kershaw "experiment" avidly, from the very beginning when they called up their dealers and asked if they should make disassembly of the "Starkey Ridge" off-limits. The response I heard was that disassembly was a major selling point! Has it paid off for them or caused endless headaches? Unfortunately I no longer ahve the connections to find out, but maybe someone else knows. It certainly doesn't seem to be emphasized in their newer knives.
For the record, I still haven't popped open my Military yet. It would take tricky milling to give it fancy scales, and there is nothing with the function that I feel I might improve. I've never said that about a Benchmade
(Why else would a bear want a pocket?)