Again, humans aren't struggling for survival anymore, so any traits or characteristics we develop aren't necessarily related to survivability. That's why, for example, lots of us have bad eyesight, which may be deadly to other species, but is just a mild inconvenience for us.
Though we do have the Darwin Awards for those who manage to be unfit even in our relatively safe living standards.
Intelligence is the most important trait of our species survival. If we were to be annihilated by a gigantic meteor tomorrow, our collective intelligence could have prevented that. The longevity of the species is different than that of the individual.
Not sure what your point is here, because obviously there's lifeforms that barely have intelligence but are so successful that nobody would go "damn, why are these things so stupid, they really should develop intelligence". On the other hand, intelligence in humans is THE defining factor. How can you imply that humans shouldn't be or wouldn't have needed intelligence?
Not really, actually, considering the only real contender for a species that has proven longevity despite global extinctions is the waterbear. Even then, they will still actually die at end of our solar system's life, or a pathogen evolves to eradicate them.
Reproduction is only one component of the ability of a species to survive, and for certain members to lack this ability does not mean they are not contributing to the longevity of the species. Ignoring the actual social issues involved of being able to choose to procreate, and whether or not one even has the ability; your entire premise is built on a naively simplified determination about actually doing the most good for humanity.
Isaac Newton, for instance, contributed greatly to the preservation of the species, while never having procreated.
As we achieve advancements in what we are capable, we also increase the ability of our species to survive by increasing the sphere of influence on the Universe around us. While we have no natural living predators, we're nonetheless stuck on a rock in a very hostile Universe that could kill us in an instant without our knowing. A single gamma ray burst could annihilate the entire species, regardless of how many of us there are. So could alien invasion, or any number of possible, however unlikely scenarios.
Stupidity is what holds us back from progress and the ability to do things. People who rise against vaccination and attempt to influence public policy are damaging to the species. But people that choose not reproduce are not, because by choosing not to reproduce they're not damaging the collective species or any members therein.
None.