Who cares about the popularity of the events when a swimmer can realistically win all of 200, 400, 800, 1500 just by being a great mid and long distance free swimmer? A sweep of more than 2 individual events should only be possible when someone is good in more than one swimming styles, or somehow they can win 100, 200/400, 800/1500 events. Obviously we need a second fly event because otherwise either sprinters or mid distance swimmer won't get a good opportunity in that swimming style, at that point it would more fair just to throw butterfly out of the program.