It's simple: the spectacle of a relentlessly bullied and institutionally oppressed too-bright-for-his-britches kid's Roaring Rampage Of Revenge against his tormentors (and absolute exculpability because Reasons and Reasons and Reasons) is primo catnip to the sort of kid likely to gravitate to SF fandom; the troubling Protagonist-Centered Morality tends to take longer to sink in.