So their use by the Americans in the Vietnam war and the two battles of Fallujah, plus their use by the Brits in Afghanistan, flown in by our own hero Price Harry was all fine and dandy and non-binary.
As with most things, it depends what you use them for...
Two days ago a Ukrainian sniper used a .338.bullet to end the life of a Russian Major-General of Paratroopers. Not overly controversial one asumes...
If I used a .338 bullet to end the life of a 5yo child, that would be quite different, no?
Thermobarics, and FAE's have a quite legitimate use - they are (primarily) anti-structure munitions, they were created to allow the destruction of protected structures like trench systems, underground bunkers, hardened aircraft shelters that normal HE weapons have limited effects on.
We used in Afghanistan in that way - we bought a limited number of Hellfire missiles using that warhead - the K version if I recall.
They can also be used - the over-pressure effect - to create helicopter landing sites in jungles/forests by stripping the vegetation (the original FAE bombs were used specifically for this), but they have another use: the over-pressure effect is great for destroying/setting off mines and IED's, and we used, and in current doctrine use, them for this purpose.
If someone is dropping a 500lb thermobaric bomb on a block of flats, the problem is not that it's a thermobaric warhead (though that's not great), it's that they are dropping a 500lb bomb on a block of flats.