I think Chuck Klosterman, in his excellent book Sex, Drugs, And Coco Puffs, summed up Cusack's appeal best:
Lloyd Dobler, of course, is the hero from the 80s flick Say Anything. A charming, lovable and sometimes goofy teenager, Dobler uttered one of my favorite movie quotes of all time, in a scene in which he tries to explain his future plans to his potential girlfriend's father:
I don't want to sell anything, buy anything, or process anything as a career. I don't want to sell anything bought or processed, or buy anything sold or processed, or process anything sold, bought, or processed, or repair anything sold, bought, or processed. You know, as a career, I don't want to do that.