I agree with you in part. I never really read the grandparent's themes of "don't mess with nature, scientists full of hubris!" from Flowers. To me it was just a beautifully sad story of gaining something precious, and then losing it, while watching yourself lose it, piece by piece. The idea that it's not something external and tangible, but is a story of mental faculties, makes it all the more tragic.

And we can draw parallels to conditions like dementia. Charlie experienced a full life of learning and decline in a matter of a few months.

I do think of this as a science fiction story. Not "hard" sci-fi, but still sci-fi. To me it's the examination of what a scientific achievement could do, but for a fatal flaw. I think it is interesting and important to the story that Charlie's experience was caused deliberately, and not through an accident or other means.