Defending motorcyclists who navigate the space between cars hits a nerve among motorists eager for a reasoned conversation on improving life on L.A.'s freeways.During his nearly 40 years as a columnist for this newspaper, my late father occasionally tweaked his readers — quite disingenuously — by belittling his cat, knowing the slur would stir invective so passionate and erudite that he could fill another column without having to do much writing of his own.