To start with, why Herbology? It's just a mundane class with no real bearing in the world, right?

Wrong. Herbology is the world around us. This particular branch of magic encompasses many different parts of our world. Who do you think first discovered the magical properties of your wand wood? What would potioneering be without the plants that are their ingredients? Plants have influenced this world far longer than any of us can guess. Empires have fallen, kings have died, and calamities have struck the world of magic and muggle alike...But the influence of this natural science hasn't changed. We still rely on plants for healing, woods for our wands, and Herbologists to keep learning. 

So, the next time you hear a person talk about the lack of need for this branch of magic, ask yourself this: Where would the world be without it?