The Titanic hit the iceberg at 11:40 PM on April 14th, 1912 and sank sometime between 2;20 AM and 2:30 AM on April 15, 1912.
April 15th, 1865 is the day Abraham Lincoln died after being shot in the head.
April 15th, 2013 is the day several people died in the Boston Marathon bombing.
I don't see how you can turn Abraham Lincoln's assassination or the Boston Marathon bombing into theme park attractions. Or September 11th, for that matter.
But this Titanic attraction has the right mixture of danger and appeal. Sliding down a platform at a 45-degree angle is scary, but not as scary as falling straight down. And this attraction could be enhanced by surrounding it with water. Most people would rather get wet than get bruised or cut or burned.
I imagine more people auditioned for "The Poseidon Adventure" than "The Towering Inferno".