They are terribly inefficient and who is going to be servicing all these hydraulics in the 3rd world? Every farming town in the USA has someone who can make custom hydro lines quickly. How many of those shops in Africa?
Please contribute anything you know about custom hydraulic lines to https://wiki.replimat.org/wiki/Main_Page - I will approve accounts for any hackernews folk who request one.
I appreciate all your points about the sort of tractor best suited to your unique circumstances. I don't see anything about our communities designs which prevent you from constructing such a machine using our parts and techniques. I think it'd be a neat design to have among all the others which can be built this way!