The semantics of Wikidata qualifiers have not been defined and and won't be enforced. It's left up to users to invent their own meanings. (In this way, Wikidata is still a lot like the prose in Wikipedia.)
We need more "curated" projects like DBpedia
Mmh, I would have rather thought that the system of qualifiers, even imperfect, was a great enhacement compared to the DBpedia model - which is a bit of a mess.
Let's take
Winston Churchill item : Wikidata tells us, for example, that he served as British Prime Minister from 1951 to 1955 replacing Clement Attlee and that he was replaced at this position by Anthony Eden.
In DBpedia, which does not use reification, we have just a list of offices, a list of successors, a list of predecessors, a list of dates, and no way to figure out who replaced whom to what and when.
The handcrafted ontology of DBpedia is certainly more consistent, but it's also much poorer. Rather than impoverishing Wikidata's class system, would it not be better to find a way to avoid horrors like
"actor is a subclass of person". I would be interested to know if there are researchers working on the subject.
Regarding the compared size of DBpedia and Wikidata, I thought that Wikidata is by nature much larger. DBpedia cannot contain more entities than there are in the english Wikipedia (about 5 million), with its very strict criteria of notoriety, while Wikidata allows any more things. Am I wrong ? (I consider of course that DBpedia and its other language versions are different knowledge bases, as is the case in the LOD cloud)