I don't mean to evangelize Polymer here - I don't actually have a horse in this race, having recently left Google and being still undecided about which technology my startup will be based upon. I think that the prefixes-as-fake-namespaces approach sucks, but of all the things you can get wrong with your web framework, it sucks a lot less than many other things framework authors do. And it enables the abstraction of "Treat web components like any other HTML tag, except you get to define their object model", which is a really powerful concept, particularly when you consider the possibilities of building the most popular of them into the browser. The problem with all existing JS libraries so far is that they become obsolete as browser technology advances; Web Components is the first one where the components may become the browser technology advances.
To complete your C analogy - yes, C sucks a lot, and it's woefully incomplete in areas like namespacing and packaging. But people still use C, because if you want to do something native it's basically the only choice, and you know that it will interoperate with basically every other language out there. And those people have managed to build some pretty impressive things with C, warts and all, even though a lot of its design choices "will never work" when programming at scale.
To complete your C analogy - yes, C sucks a lot, and it's woefully incomplete in areas like namespacing and packaging. But people still use C, because if you want to do something native it's basically the only choice, and you know that it will interoperate with basically every other language out there. And those people have managed to build some pretty impressive things with C, warts and all, even though a lot of its design choices "will never work" when programming at scale.