Before once again condemning California...
Alaska and South Dakota apparently have a similar law - if someone died by suicide or murder within the past year, it must be disclosed.
Other states have dealt with lawsuits regarding this issue. For some people, they aren't comfortable living in a house where someone died - why not eliminate them from the start and go directly to the people who are OK with it? Why risk having the buyer find out 3 weeks after the sale and sue you over it, when with disclosure they would be out of there?