Intangible matter that can neither be seen nor interacted with outside of gravity is unintuitive. It can sound like "what if we're all just in a simulation, man?" but coming from the best science apparently has to offer.
In realm of everyday experience neutrinos and proposed dark matter would be the same ghostly thing.
No, but as a posteriori reasons go "everything else couples to the weak force" is a pretty good one.
> them dark matter is unfalsifiable
Only insofar as all the ontological content of a physical theory are unfalsifiable: you can always shift complexity around between state and dynamics if you're willing to pay the price in elegance. Consider Kaluza-Klein theory, for instance. In some sense this demonstrates that classical electromagnetism is unfalsifiable - but no one actually cares.