My issues with relations named like "is-part-of" are
- the concept of "part" cannot be qualified without resorting to sub-properties
- the instance of the property itself cannot be qualified, period
- multiple tenses (was-part-of, will-be-part-of, might-be-part-of) balloon all ontologies
- the operative term "of" presents itself as a lexical afterthought
This is only one example. I can think of many others all conforming to verb-noun-preposition used to name a relation between entities (eg is-employed-by).
The impact a property-name exerts across the spectrum -- during input, storage, queries, exchange, etc. -- is one with real-life practical (read, expensive) consequences. Growth becomes unsustainable.
The most widely understood discriminator between "non-semantic" systems and "semantic" systems is that properties are named differently: in "old style" systems these names are nouns, perhaps qualified nouns; in "new style" systems these names are, uh, something other than a noun.
Consequently ontologies I see are near-doubled in size: they have both a class and a property named X, as "old style" names promulgate into "new style" systems.
I argue the industry badly needs consensus about the best practice for how attributes/relations are to be named. It affects EVERYTHING. Ontolog is the only forum I've found appropriate to this question. It really needs to be addressed - so much else is, imho, just a sideshow for all those focused on practical applications of semantic technologies.
Thanks - jmc