In response to the OP's suggestions.
1A) It would be nice, but I wouldn't see any...er logical (not the right word) to make this. Mainly because it runs into the oposite problem of having "required items", which is "items that are generally pointless for all but these very very specific things. Which brings the case "why even bother". Not a bad idea, but an odd one.
1B) Spawn Rate, if they were to spawn however, I would prefer them take a while to spawn, and at random locations. Make em difficult to find.
1C) Claiming would be the hardest part honestly and I have no logical ideas over it. (Part of me thinks SAO's method of the last person who hits it gets it, but I can see things just getting swarmed by that).
Now my own suggestions.
1) Damn near nothing can actually be done about the open world without massive changes to other things. You cannot just drop a world boss down, tell people to have at it, and expect people to care about it 1 week later unless that thing drops something epic.
2) (Though they already said they wouldn't do this) Make crafting gear close (but not equal) to the highest available raid tier. Then make leveling the crafting classes damn near impossible, but self sufficient. I am no crafter (i just started goldsmithing so I consider myself a novice at best) but I am told to make gear that is at all useful I need to level up i believe every other crafting to level 15, then 2 others to 50 to make sure I can craft HQ gear. That means that damn near every crafter has to level everything else and that is the reason the market is terrible.
Make it so I can level up blacksmith and only blacksmith and after a certain point, all the gear I make via blacksmith is HQ and boom. I no longer have to flood the market with weaver stuff because I don't need to be a weaver as well. Do this and that allows items gathered to be of actual value and thus the economy can stabilize in a way that actually makes sense. I am aware that this ruins the fun of cross-class abilities and what not, but yeah. Cross class is the reason this is a problem in the first place.
3) Why the above even matters relates to this. With gear from crafting actually mattering unless you are at the bleeding edge of endgame, means that the resources out on the field matter. That is good. Now you have to make sure there is less of it. I don't gather so I don't know if veins disappear like they do in WoW (yes I am referencing WoW), but they need to disappear. And they need to be scarce. There needs to be competition to level a gathering profession which would in turn get people to actively travel around to make sure they gathered stuff. Being random also helps, so we can avoid websites just mapping out where veins are and have those areas camped by bots. Boom, world is active with people moving around trying to find nodes and what not.