Answer

You remind me of a story that happened to me personally. My son left the Haredi yeshiva where he was studying in favor of a hesder yeshiva in Gush Etzion. As part of the crisis that developed there, and the efforts to persuade him to stay, I spoke on the phone with a well-known rosh yeshiva who wondered aloud to me what people find in Rabbi Lichtenstein, the head of the hesder yeshiva in Gush Etzion. He told me he had read articles of his and was really not impressed. Every avrekh in the Chazon Ish or Ponevezh kollel writes more brilliant things. I told him, fairly gently but directly, that he was talking like a little child. Being impressed by sparks and clever flashes of Talmudic ingenuity is for children. Systematic thinking like Rabbi Lichtenstein’s prevents all the questions those brilliant fellows are trying to solve. His approach was more serious and did not look for glitter and sparks, but for the truth and for exhausting the topic. Someone who grew up in the Lithuanian yeshiva world has a hard time understanding that.
So too with the Gra. True, he did not write large conceptual analyses, nor did he fully work through Talmudic topics the way Rabbi Lichtenstein did (at least in what he left in writing), but he has extraordinarily brilliant insights, even if they are local and not presented through elaborate Talmudic constructs. It is evident that he was a genius even from his notes.