Fewer species drink human blood, and only a handful carry diseases we currently worry about (West Nile, Dengue, Malaria). We're not aware of any species that feeds specifically on one of these dangerous mosquito species, and all of these dangerous species have other mosquito species in their habitats, so we're pretty sure that first- and second-order environmental impact of the extinction of these dangerous mosquito species would be minimal.

Though, by greatly reducing human morbidity and mortality, wiping out these dangerous mosquito populations would increase general human environmental impact. Granted, that's a Thanos-level complaint, similar to bicycles causing pollution because exercise causes people to live longer.