I never thought Flanders' flanderization was actually too harmful to him initially, he was never a complex regular character or even more than a single joke/scene character until what the third season or so? And they seemed aware that they had turned him into a one note one that they then fleshed out instead with stuff like being left handed and a good father in his own way. And it took years before he went truly crazy again at which point the whole show had become flanderized.
I mean, what I'm really saying is that one problem with discussing The Simpsons is that Flanders is getting ascribed this term that describes way more characters on it, especially regular ones. Why don't we call it Homerization or something?