My girlfriend couldn’t understand why I liked the Space Marines so much. She said the models were plain, and their rules weren’t that exciting. Well, my answer was, versatility. Sure thier models cost twice as much, points wise, as her precious Tyranids. However, even the most basic Space Marine can handle a variety of situations. Shooting at a distance? Sure they can handle it. Incoming close combat? Sure, they can handle that too. I found in my many rounds of Battlefleet Gothic that my foolproof plans were vulnerable to some small factor that I’d overlooked.
Oh, and then again, there’s always this.