It would be unfair to say that there's any one reason for the development of attack ads- only in that it would be unfair to say that there was a development of television attack ads.

Attack ads long predate electricity. Take the election of 1828. Current VP Andrew Jackson ran versus incumbent John Quincy Adams. Four years earlier, they had also opposed each other, ostensibly as members of the same political party. The election of 1824 was notably messy: Adams received 84 electoral votes; Jackson, 99; William Crawford, 41; Henry Clay, 37. As per the 12th Amendment, the House of Representatives named Adams the winner since no one candidate had a majority.

Come 1828, Adams needed to shut down the threat of the "wild" war hero Jackson. His supporters identified several events that could turn his image from valiant general to abusive barbarian. The first was the execution of 6 supposed deserters. Before Jackson's most famous victory at New Orleans, his claim to fame was defeating European-backed Creek forces at the Battle of Horshoe Bend. Some soldiers considered this the end of their duties, but Jackson understood the conflict with the Creeks as the B-story to the ongoing War of 1812. The men aimed to leave, but Jackson refused. They would later be court-martialed, found guilty, and executed. With the haziness around the end of their contracts and the end of the War of 1812, these executions were a ready-made scandal. Philadelphian John Binns attacked Jaskson with "coffin broadsides" in his papers, showing large coffins engraved with the victims' names and stories. Binns ran with this idea- later adding a dozen more coffins representing Native American civilians, duel opponents, and others.

Did it work? Not really. Jackson carried the Electoral College vote 178-83. Modern pundits actually listed the coffin broadsides as a hinderance to the Adams campaign. In this cartoon we see Mr. Binns struggling to carry his own coffins. Adams sits in one of them, holding onto the presidential chair, listing hindrances to his run. He says he'll "hang on, in spite of: Coffin hand-bills, Harris's letter, Panama mission, or the wishes of the people^1 ."

But what of television ads themselves? We see negative themes since the beginning. 1956 was the first time an incumbent ran with TV ads, and only the second to use them at all. And while many ads were quite lengthy, the 30 or 60 second clip was not uncommon. This ad by Adlai Stevenson attacking Dwight Eisenhower is instantly familiar to us. How many ads in the past few years have followed the "Here's the candidate promising something, but here's what he actually did!" formula?

You'll see lots of articles that make a huge deal out of the negative sentiments in the Daisy Girl ad- but today's ads can't claim a "lineage" from it. The main strategies have much earlier roots, and are hardly even present in the ad at all. Goldwater is never mentioned, neither candidate's face appears, it is thoroughly negative, and any actual political issues are only implied, never directly stated in any way. Compare that with Hillary Clinton's 2016 ads, which featured plentiful direct clips and quotes from Donald Trump, or Trump's 2016 ads, which often concluded with an inspiring "Here's how America will be great!" section after slinging its mud. Rather, the Daisy Girl ad pops up in textbooks and newspapers to this day more because of the way the negative message is presented. It's short, simple, and remarkably abstract in a way that even modern ads are not.