In fact, one can find a good deal of variability in the handling of this term.
While I believe that the legacy argument is essentially correct, it speaks more to etymology than to evolved usage. On the other hand, I believe the relatively recent work by Joel Burnett is superior to the far too facile "royal we" offering.
The phrase used by Joel S. Burnett is "concretized abstract plural" (A Reassessment of Biblical Elohim - SBL Dissertation Series 183), originally presented as the author's doctoral thesis at John Hopkins University, 1999, with P. Kyle McCarter, Jr.,serving as Dissertation Advisor. He writes:
- The usage in question, as explained in GKC [Gesenius' Hebrew Grammar - JS], is a variety of the abstract plural, which sums up "the conditions or qualities inherent in the idea of the stem. Examples include zequnim "old age," sanverim "blindness," onim "might," 'esot "counsel," harapot "contempt," neqamot "vengeance," and negidim "nobility" -- only a small sampling of a category that is abundantly represented in Biblical Hebrew. ...
The term "concretized absract plural" is preferable to others that have been mentioned because it is more precise and not susceptible to the mistaken notion that the plural form implies a quality of might, excellence, or superiority which may or may not characterize the referent of the word. [He here notes Otto Eissfeldt's reference to the grammatical category "substantivisches Abstraktum."] Again, in the case of the abstract plural, the emphasis conveyed by the plural form pertains not to the object denoted but to the meaninf of the substantive itself. Thus the suffix form of betulim in Lev. 21:13 ("And he shall take a wife in her virginity") does not mean "mighty virgin" [or majestic virgin - JS] but "virginity," emphasizing the idea associated with the stem, i.e., an abstraction.
The book is well worth reading if you're at all interested in such things.