Why is it necessary to protect rare oviparous, marsupial, insectivorous and bats?

Rare oviparous (echidna, platypus), marsupials (koala), insectivores and bats (bats) need to be protected, because many of them are on the verge of extinction due to extermination (platypus due to valuable fur, bats due to for beliefs, ignorance) or because of violation of habitat conditions (pollution of the environment, deforestation, drainage of river floodplains. But they bring great benefits to humans and the environment, they are an important link in the biological chain: bats eat insects that harm forests and carry causative agents of dangerous diseases (malaria, leishmaniasis).