People expect that their property will be distributed according to their will when they die. This is generally true, but the testator may have made decisions during his or her lifetime that override the will provisions.
When the marriage is over, former spouses usually want their property to go somewhere else when they die. At least the revocation-on-divorce statute assumes this is so and renders transfers made to the other spouse null and void. The statute became effective in 2001, but it now looks like it may affect transfers made before then.