Why in this day and age can't we have the original, and better, ending from the book?
Are we as a world so terrified of the hate and sorrow in this world, that anything which ends on anything but a "Flowers and Puppies" note is considered horrid? Are we so pathetically trying to blind ourselves to the never-ending nature of the unstoppable death, hate and abuse in this world that even in our films, we cannot bring ourselves to show it?
In short, I am against the raping of good, albeit depressive, endings in exchange for "Oh look, it's all right!" endings.
I am Legend got it's title for a completely different reason in the book. Wikipedia it if you want to find out what it was.