@metsfan: do you always have to argue your point into oblivion? Learn to shut up please.
Regarding the point at hand: I don't play much 1v1, so I don't really care what happens to that. I don't think this suggestion is necessary for multiplayer games, though, and has some small but significant disadvantages.
Due to the political nature of a multiplayer game, players will team up on the player with the higher income, making a dropped bonus far less likely to be gamebreaking. Even in a 3 player game, if the player who begins also drops a bonus, the game is still far from played, because the other two players together are almost guaranteed to have an income to match that of the player ahead, even after his attacks.
In fact, seeing someone drop a bonus and get the first turn in multiplayer is worth experiencing once in a while. It teaches diplomacy, gives the players in the worse position the chance to feel better about themselves because of a win where everything seemed to go against them, or gives a weaker player just the boost he needs to get one of his rare wins.
I wouldn't be devastated if this was implemented in multiplayer, but if it isn't broken, don't fix it. (Voted only for 1v1)