The Semantic Web is just a way to augment and improve the EXISTING Weband all the existing relationships, groups, communities, social networks, user-experiences, apps, content, and online services on it. It doesn't replace the Web we have, it just makes it smarter. It doesn't replace human intelligence and decision-making, it just augments human thinking, so that individuals and groups can overcome the growing complexity of information overload on the Web.
Part of the problem, I think, is what "semantic" implies: thought. Just how we get meaning from syntax a problem that neither cognitive science nor centuries of philosophical thought have yet managed to explain. The problem is one of naturalizing representation and meaning. A lot of the push back to the idea is push back to the size of the claim.
The "augmented Web" isn't nearly as sexy, but I think it's a lot more accurate.