But I'm already alive, so if I'm no longer alive tomorrow morning it'll mean that I died during the night - which involves a certain amount of suffering.
If I die without knowing it, it would cause me no suffering at all, but my loved ones would still suffer, and my life, which is already established as being happy, would have been cut short for no good reason.
None of these things are true for a non-conceived human because they can't feel pain and have no established ability (or desire) to experience a happy life.
This article is generally sound, but I'm not sure I agree with the idea that the experiences of the current generation are trivial compared to the possibility of future generations. Future generations don't exist yet and therefore have nothing to lose, while living creatures have everything to lose.
Sure, a human could be conceived and live a reasonably happy life (if they're lucky), but they could also never be conceived and be none the worse. When we, as living humans, think of the possibility of never being born, we are saddened because we know what we have to lose, but a pair of non-fertilized zygotes has no such feelings.