I know that some phones have a water sensor inside that the manufacturer can use to deny warranty claims when they can prove the phone got wet. It is scary to consider that now the phone will simply dissolve when it gets wet. I guess I got spoiled when my wife's Motorola pager was run through the washing machine 26 years ago. When it was retrieved, we opened up the pager, removed the battery, and left it out to dry. The next day, we replaced the battery and the pager worked perfectly. I'd vote for reliable electronics and a comprehensive electronics recycling program.
It is interesting to note that while many technology companies, especially in the less developed countries, are working intensely to increase the lifespan of electrical gadgets and devices so that their owner can use them longer, ours seem to be focusing more on making their lives shorter. Personally I subscribe to the first field of though and I still have a Pentium II computer in my garage that still works and which I boot up once in a while just for the kick of it. I would rather lose my Smartphone and then block it that have it with me only for it to be rendered useless within a few years.
While the object of reducing waste is noble, the solution of building is self destruction isn't satisfactory to anyone. To the user, having several more guaranteed modes of failure certainly doesn't make the product more effective. While one mode of decomposition may take years under a "normal" environment, certain environments may very well accelerate it, causing warranty heaadaches for the manufacturer. I think a far more practical approach would be to aim for an efficient recycling process. Wouldn't if be nice to be able to simply dip the spent product into a magic potion, with a bit of electrolysis, that would separate the components into reuseable chemical compounds.
If the proposed dissolvable electronic project has been keenly looked into considering both health and environmental issues, then I believe it is a good idea. If the gadgets can fade away when their life span is over then it will help solve the problem of pollution arising from electronic stuffs.