Here's some background on this border:
http://en.wikipedia.org/wiki/WagahAnd yeah, it seems kind of silly and pompous, but most cultures have some ceremonial things that look really silly to others... The changing of the guard at various locations/memorials comes to mind (Lenin's tomb in Red Square (Now the tomb of the unknown soldier), changing of the Queen's guard in the UK, our own changing of the guard at the Tomb of the Unknown Soldier), etc...
(And no, I'm not trying to denigrate the Tomb of the Unknown Soldier or it's guard, just saying to someone not familiar with the significance of that place and the ceremony, it seems kind of odd...)
Article on "Changing of the Guard" ceremonies all over the world -
http://en.wikipedia.org/wiki/Changing_of_the_guard