Hemp seeds have failed to catch on as food for a simple reason: they're too strongly flavored. The nutrition claims are largely true, and the flavor isn't terrible, but in order for hempseed to provide, say, 15 grams of protein to a meal, you need to eat about a quarter of a cup of hempseeds. Imagine eating a quarter of a cup of sesame seeds. See the problem? I think the missing link here is some kind of fermentation process that produces something more palatable.

As for the fiber, it's a relatively unremarkable cellulosic fiber. It is rather coarse and contains about 8% lignin, which means hemp fabric is relatively stiff and rough, limiting its application to clothing beyond its branding power (and shoes, where it works well). However, it is useful in composites. Hemp is apparently being used to make composite panels for several cars in the present day, although the actual volume in this market is not so high. The asterisk is that there are lots of other similar fibers (jute, linen, lyocell) that work well in composites, and it's the resins (polyester) which tend to be both more expensive and environmentally problematic. If some kind of more eco-friendly resin technology appears (don't hold your breath) it could become more widespread.

Other claims, e.g. hemp as a building material, are just wrong (hempcrete is not structural). Hemp rope was replaced by manila which has better moisture resistance. Hemp as a biodiesel precursor is unremarkable.