The problem is that if devs were to make another crafting or gathering class, they'd effectively have to do that by finding a solution to a problem that currently doesn't really exist. Sure, there could be a class dedicated to farming hides, but that could just as easily be done by any combat job going out and killing mobs. I even suggested it before; called it Scavenger, said it could farm specific points for leather scraps or other crafting items that are normally attained through combat, even have a story that could provide insight into the history of various places we wouldn't otherwise get with any other stories in the game, but it's still a solution to a problem that can barely be considered a problem at all.

Other things you suggest are things we already have. We already have a painter that works in Idyllshire that works off of our Sightseeing Log. Melders work off these items called Materia, which is made from items we convert (break apart) and can be melded to gear for the benefit of an increased stat. As for the Farmer, I'm fairly sure it got scrapped because making a minigame like that would just be a waste of resources and once again, a solution to a problem that doesn't really exist.