The RDF part of the semweb idea encourages us to be extremely explicit with what we mean with our data. This helps our end users because it removes a lot of guess work. What was obvious for us as maintainers is not obvious at all for the biologists who need to do stuff with our data. e.g. http://www.uniprot.org/changes/cofactor (going to be live soon) it's a small change from textual descriptions of which chemicals are cofactors for enzymatic activity to using the ChEBI ontology. This allows us to better rendering (UI) and better searching. It also makes the difference clear between cofactor is any Magnesium or cofactor is only Magnesium(2+).
In the life sciences and pharma semweb has a decent amount of uptake. For the very simple reason that this branch deals with a lot of varied information and often mixes private and public data. RDF makes it cheaper for organisation to deal with this.
SPARQL the query language has a key feature that no other technology has in the same way. Federalised queries: if I am in a small lab I can't afford to have datawarehouse of UniProt, it would cost me 20,000 euro - 30,0000 euro just to run the hardware and maintain it. As a small lab I can use beta.sparql.uniprot.org for free and still combine it with my and other public data for advanced queries. Sure uniprot has a good rest interface but it is limited in what you can do with it in ways that SPARQL never will be.
SPARQL is only interesting as a query language since last year. Schema.org is only interesting since last year. JSON-LD is only interesting since last year. Semweb is finally growing into its possibilities and making real what was promised 17 years ago now.
Of course even in the life science domain many developers don't know what one can do with semweb tech, and semweb marketing is no where as effective as e.g. MongoDB or even Neo4J is. So uptake is still slow but it is accelerating!