Theres lots of time that goes into mobs like ideas, designs, features, and new blocks. The reason why people mod them fast is because they just copy them
At this point Re-Logic is more of a chad game company than Mojang. Re-Logic always listens to their players' suggestions and 99% of the time they think that idea is a great idea, why else has Terraria gotten the popularity it has today?
My Pack Of 69420 Wolves, Ready to protect me from any skeleton/enemy: Am I a joke to You?... but I respect Your opinion. People vote whatever they want.