Absolutely agreed. They even gave that one-off Inquisitor in their vignette TotJ series
a pretty cool design... and then he dies like a chump, never even getting named. The Ahsoka trailer reveals another (presumed) Inquisitor, also with a
pretty cool design. I fear they'll pull the same stunt again.
Otherwise, it'll just be another Reva (as seen in the Obi-Wan series), which was just... a garbage plot.
I get that Rebels had the draw-back of being a kids' series (more so than TCW), so I'll dock no points for how nerfed and useless the Inquisitors were, there.
Fallen Order, however, did a bit of a better job, and the reason Reva is such a useless character is that's she's very obviously a knock-off Trilla. An inferior copy of the same idea.
They could have done a lot with the Inquisitors, but they wasted the whole idea nine out of ten times.
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Palpatine didn't give a single flying fuck about the Rule of Two.
No, those existed for more 'mundane' political dissidence. The Inquisitors were for the Force-related shit, largely because Vader (however powerful) is just one dude and can't be everywhere. There are still Jedi in hiding, so having Inquisitors in the early period of Palpatine's rule is perfectly sensible, and indeed much-needed.
A case can be made for going "night of the long knives" on most (or perhaps even all) of them once you're confident that virtually all Jedi have been hunted down, though.
So... Sith business as usual?
Not doing so would also pose a danger -- quite possibly far more acute -- of allowing too many Jedi to slip into hiding. Possibly to places where they might gather their forces to begin an insurgency.
Palpatine, by the way,
consistently took enormous risks. He's very typically psychopathic in that regard, as in all other regards. So this argument by no means stops him from doing a thing.
That's just plain wrong. Not one single source indicates that the Jedi were "breeding out" Force-sensitivity. On the contrary: it's made explicit (in both continuities!) that the Jedi only ever discovered a very small faction of the Force-sensitives. In most untrained ones, the Force-sensitivity would fade away due to lack of practice.
Even if you assume that Force-sensitivity is wholly hereditary, then, it's still undisputed that the Jedi practice of taking on some of the Force-sensitives into their Order had no appreciable effect on the genetic substrate of "Force genes" among the wider populace.
Moreover, Force-sensitivity explicitly
isn't (exclusively) hereditary. It can and does appear in individuals at random, regardless of their genetics.
In short: neither the activities of the Jedi nor their extermination had any meaningful effect on the number of potential Force-users being born in the galaxy at any given time.