But those dangerous events are one thing that drive humanities development, and thats one thing I don't see ever changing. They are tragic, they are painful, but as Kirk says himself, "How we deal with death is at least as important as how we deal with life"
You're talking about the needs of the story - to confront the characters with challenges. I'm talking about the impulse of the characters within a story - to try to mitigate or evade those challenges wherever possible. Like we all do in real life.
The writers will be able to throw challenges at the characters regardless, since they are in total control of everything that happens. There's no reason to have the characters weirdly try to help the writers inflict trouble on them.
Spock can warn Starfleet about everything he knows about, and the writers will just invent a hundred other things that Spock doesn't know about. That shouldn't stop Spock from trying to warn Starfleet. He doesn't realize he's a character in a story, and his warnings are futile and will merely result in a cascade of new Doomsday Machines to replace the one he knows about.
I just want to see Spock do what he should do, namely try to warn Starfleet to the best of his ability, if for no other reason than that it would be stupid and irresponsible for him not to. Plus, do we really want to see a replay of the Doomsday Machine we know about?
I'd rather that threat be eradicated off screen, and the writers get cracking on the threats that will occur regardless of Spock's warnings - or even better, because of Spock's warnings. What if the Doomsday Machine was slated to mow down some brand new alien threat, which now will be spared to wreak havok on the Federation?

Hee hee.