They could take some of the random special public events that are attached to various updates, and put them all into rotation. Right now we only get Taken invasions in all patrol zones-- no more Wolves, no more Blades of Crota. Is there any reason why these things can't come back, so that there's more variety?

Well, Crota's dead, so no blades, and Skolas is locked up, so no Wolves. That would be that ludonarrative dissonance you talk about :-p

They don't care about that anyway. There's no more dissonance in having Skolas alive and free NOW than there is in having him still be free in early HoW missions that run as the Daily Heroic after you've already done that mission, or even after you've completed the Skolas fight in the Prison.

There's no more dissonance in this setup than there is in having Regicide be the Daily Heroic after you've already defeated Oryx in the raid, to say nothing of defeating him multiple times in the raid, just like every other boss and miniboss in the game.

If they want to create narrative continuity, they should do so. If they don't, they shouldn't make the content in the game feel even more sparse than it already does by withholding it on a narrative basis.

They might have some reasons for doing so, but I really hope that isn't it.