If you want to gather or craft, you can already do it.
If you want to participate in FATEs, you can already do it.
If you want to use gpose, you can already do it.
If you want to find scenic spots, the sightseeing logs already exist.
Nothing about what you propose is really adding anything new to do to the game outside of giving trolls the ability to set up a tent over the location of known quest objectives or gathering nodes then walking away to watch players trying to do those quest objectives or gather get upset when they can't. Going into the open world to do the content that already exists there is going to be a lot more unpleasant when you're stuck looking at a bunch of abandoned tents.
It's a decent idea for a co-op game where there's only a handful of players present by invitation on a local client. It's a bad idea for a MMO with thousands online sharing the same game server.
There's already quite a bit of content in the open world zones. Some of it is one time - MSQ, side quests, sightseeing logs. Other is repeatable - hunts, FATEs, gathering, beast tribes. There's plenty already going on there for players to do if they're interested. It's okay for some players not to be interested in the content there.
What needs to kept in perspective is that the open world zones are primarily a vehicle for the MSQ and SE has to be cautious in the additional content that gets added to them. Add too much content so more players are in the zones at all times and congestion/latency becomes an issue. It's disruptive to the players working on the MSQ, not to mention the other content.
I'm not saying there isn't room for SE to add a bit more, but it has to be done with caution and for good reason. At least make it content that is different from what we already have instead of just reusing the content that already exists to give more rewards.
I would imagine the players experience issues during the hunt trains would argue it's not handling them.
Having a bunch of tents in random locations being added into the list of things the servers need to communicate and local clients need to render won't help.