Is the World Wide Web useless? If the answer to that question is "No" then its contradictory (albeit inadvertent) to presume a Semantic World Wide Web is useless.
Granted, the messaging behind the Semantic Web meme is simply as bad as it gets, especially for something so important.
The World Wide Web was a Semantic Web from inception. The Semantic Web meme should really have been presented as a new formalized insight into what already existed, since Web inception.
Links:
[1] http://bit.ly/evidence-that-the-world-wide-web-was-based-on-...
[2] http://kidehen.blogspot.com/2014/03/world-wide-web-25-years-... .