Why are the assassinations of Presidents Garfield and McKinley not treated the same as those of Lincoln and Kennedy?

Presidents Abraham Lincoln and John F. Kennedy were the first and last presidents to be assassinated, and this is one reason why they are better remembered. This is not the only reason, however. Historians generally regard their presidencies as more important than those of James Garfield and William McKinley.
Lincoln is loved and remembered for overcoming his humble background and rising to the presidency. He led the country through the Civil War—the greatest crisis in its history. He set the slaves free, too. Lincoln always tried to do the right thing: he was a man of integrity. His assassination—the first presidential assassination in American history—was a sad and shocking event.
Kennedy is well remembered for his youth, charm, and the fact that he was the first and only "modern" president to be assassinated. His death marked the of the glorious era of Camelot. Another reason why is is so well remembered is the speculation over the motives of his assassin: Lee Harvey Oswald. Some believe believe Kennedy's murder was the result of a conspiracy. Also, his last moments were captured on film and that has given Americans an indelible memory of that tragic event.