I'll grant him this: it is indeed hard to come up with something useful to go with what we have now. However, what if what we need isn't something to get new material types but old material types? Therefore I propose this class: Hunter.
Disciples of the Land are classes that gather materials from nature. Well, aren't animals and beasts part of nature? So why not have a gathering class that can get meat, hides, and other various goods off such creatures at a far higher rate than simply killing mobs as a Disciple of War or Magic (which we already know has very low drop rates in expansion zones that make us rely on Retainers more than going out and farming)? You could even use different tools to acquire different types of materials, such as traps for hides or spears for meat.
Open to thoughts on the Hunter concept or anything else that might prove useful alongside Mining, Botany, and Fishing. Let's give YoshiP some good ideas for a 4th Disciple of the Land!