Nintendo's O'Leary enjoys talking about Advance Wars
According to O'Leary, the change in tone (from the bouncier, happier style of the games to a more Linkin Park kind of thing) had less to do with reflecting the harsh reality of war and more to do with players just wanting something different. So, indirectly, you guys sent a meteor to the game's world because you were bored. The change in display, now featuring the map on the bottom screen and info on the top, was a streamlining effort to allow "all of the action (to take) place on a single screen." It's, again, part of refreshing the whole series.
Read the full interview for tons more info gleaned from O'Leary's conversations with the game's Japanese developers. We got the feeling that O'Leary may just like Advance Wars.