In game product placement ads are one thing,
They are a cheap attempt at exposing thier product to the masses more often.
They can also add more realisim to the game.
In some cases be really good for the game such as the Grand Turismo series.
But they are not (so far) intrusive or inflamitory topics or products.
In the case of the advertising method with the political ads, they (developers) are leasing space in the game for ads. The current election may be historic, but it is also going to go down in history as one of the hottest debated one.
As pushy and as much money that can be involved, you can expect to hear "This is aproved by Barack Obama" before a multiplayer match in the near future.