Although previous release had not yield much feedback so far, I've kept hitting this nail of views, aspects and perspectives and eventually produced a new version of SPEK vocabulary. The new release is as simple as can be, although the RDF schema is quite weird at some points. It introduces a spek:Description which is not formally defined as subclass of rdf:Description, but which looks really like it. RDF editors are variously happy with it. SWOOP beta 2.3 seems to yield the best results among all I tried.
Hubject is no more an explicit class in this version, because I've figured out that about any resource could be used as a hub. I've kept "spoke" as the property linking a view to the resource it describes, but changed the direction : the spoke is directed inward to the (hubject resource), not outward from the hub.
As an example, I picked the "Air Pollution" hubject as defined by Wikipedia, and four different views : a term in a glossary, a descriptor in a thesaurus, a category in a taxonomy, and a class in an ontology.