Very well written introduction to some of the problems with semantic web dev.

Personally I think the reason it died was there were no obvious commercial applications. There are of course commercial applications, but not in a way that people realize what they're using is semantic web. Of all the 'note keepers' and 'knowledge bases' out there, none of them are semantic web. Thus it has languished in academia and a few niche industries in backend products, or as hidden layers, ex. Wikipedia. Because there wasn't something we could stare at and go "I am using the semantic web right now", there was no hype, and no hype means no development.