If 'X is good' were exclusively optative in meaning, then speakers would have been radically misunderstanding the meanings of their own utterances for hundreds of years

Indeed there is something odd about the very idea of a disguised optative. Of course, it is possible to give orders or express wishes by means of sentences that are grammatically in the indicative mood. Henry IV’s “You have good leave to leave us”, is grammatically in the indicative but it is merely a slightly less curt variant of the obviously imperative “Worcester, get thee gone” (Shakespeare, Henry IV, 1.3). But when we use indicatives to express wishes or convey commands we are engaging in c