Perhaps this is as it should be, since most of the time, someone who attempts suicide in front of a camera is clearly a victim of the dangerous fantasy of rescue, hoping to be "saved" before his suicide is successful. (Of course, changing the law to forbid intervention with suicide attempts would be better than the current situation for both those who genuinely want to die and for those who engage in potentially self-lethal behavior in order to be saved.)
Is there ever a good reason to die on camera? I propose two possibilities, both with limits.
1. Not wanting to die alone
It is understandable for a human being who genuinely wishes to die to also not want to die alone. Many people call suicide hotlines for this purpose, rather than in hopes of rescue. Suicides regularly seek each other out in order to die together. In his book Why People Die By Suicide, Thomas Joiner refers to a 2004 Chicago Tribune article about people who commit suicide by jumping in front of trains:
Almost always, suicide victims [sic] peer into the locomotive cab in their final moments. They stare right into the eyes of the engineer, perhaps reaching for a last human connection.
. . . [Metra engineer Raymond Baxter says] "I've heard other engineers say [people committing suicide] look at you. I don't know why they do it. I sure wish they wouldn't, because the picture stays with you. You try to forget about it, but you don't ever, really. It ain't easy."
The desire for human contact at the last moment is poignant and understandable - but it is awful to force this attempt at connection on an unwilling train engineer. It would be much better if a suicide could agree with a willing person beforehand to be with him while he died - even if it only meant watching over a web camera. This would spare the feelings of unwilling witnesses, such as the poor train driver, yet it would not force upon a suicide the cruelty of dying alone.
As it is, there are major problems - most of them legal - faced by people who would comfort a suicide in his last moments. In a 2007 This American Life episode (How to Rest in Peace, at 39:35) a son ("Edward") describes helping his mother to commit suicide, at her insistence - but not being able to be with her while she died, for fear of being prosecuted for having a role in her death. His mother was forced to choose between dying alone and staying alive against her will - and chose to die. But she should not have been forced to make this choice.
Barring major changes in laws against assisting suicides, pre-arranged company via web camera offers a measure of comfort to a dying person. (Still, allowing one's suicide to be viewed by one person or a few people seems more justifiable than publicly broadcasting one's suicide to the entire internet.)
2. In the interest of providing information
Despite hysterical claims to the contrary, there is very little information available about dying certainly and comfortably. (Even The Peaceful Pill Handbook is not ultimately helpful without access to barbiturates.)
However, if a suicide were to demonstrate a method in the interest of increasing available information, it would be a public service to other would-be suicides to share the method and experience - good or bad. Others would be able to see first hand the use of the method and its apparent effects. While some viewers might find this disturbing, I think it is ethical as a civil disobedience against the unethical suicide prohibition, especially if the video could only be accessed by those who specifically sought out such information.
From the This American Life episode mentioned above, at 51:20:
Ira Glass: It just seems so sad that she has to be alone at that moment. It seems like that's the moment where, of all moments, she would want somebody with her to hold her hand and comfort her.
"Edward": It was terrible. It was terrible. Exactly. That was probably the worst part of it, that she had to do it alone. Me and her other family members could not be there, because we live in a society that does not respect people's desire to control the end of their life.