I agree with you in that the idea of life becoming boring, on the whole, as a reason for committing suicide is pretty silly, maybe even dangerous.... but as I said, in the context of this story, and considering who it was that was perpetuating this particular idea, it does make some sense. The whole episode was about what was right, ethically? Janeway didn't magically make the decision; we have to make it ourselves, and you're right -- its kinda shady. But nothing's ever clear-cut.