The media wants the money from the political ads. Election years are big revenue years for the networks. The money goes to them, after they stirred the pot enough to have competitive races. Political ads drives this madness. The candidates raise the money and the media collects it with political ads.
No question,its always about the money. However media bias is over the top with many of them.
If politicians were smart they would realize political ads do not add a single vote. They are the biggest waste of money next to a phone bank.