That's strange...
For me it's anticlimactic if someone like, say, Barrichello is behind, let's say, Piquet in clearly better machinery but cannot get past. Fair enough, seeing the car behind hunting for place to pass is fun for a while but that wears out reasonably quickly because the car behind has to fall back to save tyres and wait for the car in front to pit so that he can get past. And because it's so hard in most cases it seems like the drivers don't even bother unless they have way better machinery and just wait for the pit stops. Also, because overtaking is so hard you don't need to defend that hard, the aerodynamics do.
Yesterday I saw two spectacular battles for position in cars that can overtake. One was in BTCC where Jason Plato desperately (and succesfully) protected his position against Matt Neal and the other in NASCAR (of all things) where Jimmie Johnson hunted down Tony Stewart few laps before the finish line to take the win.