Oh why is the "I" capitalized in English

NYT Magazine writed waxes poetic as to the derivation of the capitalization of English's first-person-nominative-pronoun. Is it because of some odd sense of self-importance? Is it associated with our collective greed as a culture? Doubtful. I think it's another hook thrown in there to confuse foreigners -- see all of the -nyms and -graphs in our language.