They are an invasive species in most of the world. Wiping them out is restoring the ecosystem.

Targeting the disease-spreading species is the point, there are 3,500+ species and only a handful of them cause widespread suffering in humans, and the predators of those are generalists and would survive on other insects.

Aedes aegypti is native to Sub Saharan Africa. It evolved to lay eggs in vernal pools and tree trunks.

Probably humans. Arguably worse.