The old-timey logic that "Red Kryptonite can do anything!" is a very Silver Age story-generating idea, just as Gold K only existed so that Imaginary Stories could permanently for realsies depower Superman forever, making it something that could never be used in actual continuity without curing or cheapening it. So I get why they changed that, giving Superman amnesia effectively lets you do "What if Superman stopped being Super?" stories with a built-in reset button.
At some point, I think around Smallville like >>96148947
said, Red K became just something that makes Superman act like a dick, which has the same "Superman has become a problem!" effect, but in a way that's both more "badass" and "real" to the shifting demos of comic readers.