It's this element, I think, that's tripped many up in hearing these operas. Flute is popular but insufficiently populist; conditioned by decades of our pop culture one may feel the ruling know-it-all Sarastro sinister or implausible and the Queen's initial mission the better plot for the piece. But revolution is rejected, and resentment itself is brought on stage and, in the equally flat persons of the Queen and Monostatos, literally expelled (while their counterparts -- Pamina and Papageno -- are taken in). A neat moral, far from Beaumarchais -- who anyway had his own revolutionary issues the following year.
Clemenza, by contrast, humanizes both authority and its would-be usurper; in fact the drama is substantially internal to the two of them and the conflicted man in between. But if Tito's celebrated humanity and goodheartedness are enough to make the Romans forget his quasi-usurper status (as Vitellia laments in the very first scene, his father seized the throne from hers), they don't, for many, excuse his tyrannical hold on three hours of our attention. His person isn't secure for that time, but his moral possession of authority is -- and doesn't that, today, seem to beg the real question in any regicide plot? (Philip II, e.g., provides better dramatic possibilities, and is felled more strongly onstage.)
One understandable reaction has been to minimalize the public aspects of the piece and focus the production on the private and interpersonal troubles by which the opera breathes. Stephen Wadsworth's stand-in-front-of-a-brick-wall production for NYCO was along these lines and, I think, admired for it. But even the most personal anguish here isn't just personal. Is the prominence -- in Sesto's and Vitellia's key arias -- of the Mason-tinged basset clarinet and basset horn but coincidence? And without the politics as a frame, what connects the private star turns?
Ponnelle's simple production for the Met, currently running, sets the frame with two clear strokes -- a scrim/backdrop of collapsed columns, statues, etc., which shows during the overture, and a handsome set of worn but intact columns and statues, which is revealed afterwards. (By Act II the collapse figured on that scrim now appears on the set.) The contrast is plain and powerful: civic order v. disorder -- indeed, collapse -- the threat that birthed imperial Rome in the first place.
Is it true to the text? Perhaps not; despite the fire, Vitellia desires rule, not chaos, and calls off Sesto when she thinks it can be acquired without murder. But disorder and anarchy was surely a (if not the) prominent context of Clemenza in 1791, with Emperor Leopold's sister Marie Antoinette long since tossed from Versailles & fatally caught by an upheaval soon to seek not just power but obliteration of the old. At the time, the piece may have seemed insufficiently monarchist for any particular ruler's taste, ensuring Tito's authority at the cost of his power. But that's not our concern. Enough to note these works' recognition in man* of murderous envy against even the most enlightened authority. That impulse persists today. Soon, it will command nuclear weaponry.
[*Feminists may take umbrage that this resentful force is, in each of these similar plots, identified with a woman, but that's another matter.]