Because it is different and therefore not acting. Written many posts about this in the past but in short the main point is as follows,
The Devs do not nit pick who is allowed to step foot on a world. At all. (Outside of flat out banning from the game)
The players will do this for their „Anti-Social“ reasons. And because of this it also gives the players power over some situations they should not be allowed that kind of power over.
I’m a moocher lol… I want private worlds so I can build on someone else’s 
You can build on mine… . maybe. . if you are nice. . and they ever allow them!
Sweet! Lol
If that’s the only reason then here are some counter-arguments:
First, people have a very strong motivation to let anyone play on their planets: footfall. Everyone loves footfall.
Second, shops. Another strong motivator to leave the planets freely accessible.
Third, showing off their builds. Which is, you know, kind of one of the main reasons for building cool things.
So I don’t think that many people would lock the planet out completely.
They might stop you from plotting there without approval, which is fine by me and the main reason to have rented planets in the first place, so that you don’t wake up to find a giant gleam rectangle ten blocks from your bedroom window one morning.
But, even if they did lock their planets out completely, how does that make the universe any emptier? That remains unexplained. They’re still in the universe. They still would have to get out of their anti-social planet to trade and mine gems and stuff.
They’re interacting as much with the rest of the playerbase as they would if they just had a locked base buried underground somewhere (and hey, I do have one of those! 
I still run into people all the time.)
You could argue that they might spend more time in those anti-social planets, but is that really any different than spending hours at lava depth mining for gems in tier 6 planets with no other players in sight?
So to me it remains unexplained how any of that would make the universe emptier, so I guess it’s still witchcraft.
It isn’t but most people have already read the quite an amount of posts i made on the topic, and therefore to save people from wanting to rip their eyeballs out. I decided not to make a long post repeating the same Information.
I don’t love foot fall. infact I don’t even like it.
Yes they are valid motivators, and most reasonable people might keep their world unlocked however there will be people who don’t because they live in fear.and that doesn’t change the fact that some people can do this and can create some not so nice situations involving loss of assets, which is something someone else should not be allowed to do to another player in an PvE only game.
I never really said it makes the universe emptier. But it can give the illusion that it is even emptier then it really is. We already have an extremely small player base, that on top of the weekly thread about how the game is dying, portals are closing and so on. tells me that as it stands right now. people are coming in to the game thinking it is empty even thou you and me both know this is not the case. If everyone and their mother had their own world, this would greatly amplify this effect, even if it is just an illusion.
Technically. Yes.
I have ran in to other miners while mining for gems at low level when there were no other players in sight. because you know what happened? someone else came to where I was at. This would not be the case if people could simply lock themselves in their own world.
And perhaps it would feel less like it’s dying or empty or whatever if all the people that stopped playing / building out of frustration with land disputes and other issues, came back and started being active in game again because of the reassurance that their stuff wouldn’t be messed with in a private world, like the person that created this very topic, for example.
A locked world is just a very large base. You still need to get out of it to get different colors of materials, gems, metals, advanced resources, oort stones, etc etc.
Edit:
It just seems counter-intuitive to argue that the things that are driving people away from the game make the game feel more populated. And particularly ironic on a topic about someone leaving the game because of those things.
This makes no sense. It would feel even more empty if everyone was playing on their own private world. especially to the new players. We don’t need to dilute the player base over even more worlds, We will have a decent amount once T7 and T8 worlds come out. This makes even less sense to dilute the player base over worlds that very few people can access. Esypicaly since the reason i feel most people are leaving is due to lack of content.
But i have about done it with this one for now. I don’t get the [[Curious Obsession]] people have with wanting the power to lock people out of other peoples stuff but yet they complain to the high heavens if someone builds next to them. If it is not enough to prevent someone from plotting, and they really feel the need to prevent people from even stepping foot on the world. i feel they need to play an offline game.
I do not want to start fresh only to get new neighbors again and having the same problem. Besides, moving planet is not as easy as that, as not all planets are the same and none of the higher tier worlds come close to the beauty of Antar VI (Opinionated question). Also, I spent 400 hrs building this town, farming materials and so forth. One does just not tear and rebuild just like that. Not when time is very limited.
I cannot pre plot as I do not have enough plots, as I mentioned in my rant. I would have if I had unlimited plots.
@Arkhainn Yeah, I may do that, still got 16 weeks of gleam club. But I just feel like it’s ruined for me.
People saying private worlds would ruin the game, I disagree. During my time with this game, I constantly see people asking for private worlds. But right now I will not be one mostly because of time but I am also not gonna play when I got time because I am discouraged to play and build when there is still a chance of private servers coming out.
Let’s try an experiment then. I’ll go make a poll. 
Go ahead. I know My view is an unpopular opinion based on the debates i have done in the past. As people seem to want as much control as possible. I don’t need a poll or you to tell me my opinion is unpopular.
It’s not that your opinion is unpopular, I just have a feeling that most people would let everyone visit their planets if they rented one.
And thats fine. But the fact still remains that the same people who create the problems we are talking about now, can use the Ability to control who can or can’t come on to a world to create different more serious problems. which is why i say its a power that no player should have.
And if it is really supposed to be apart of the main universe, then it should be Apart of the main universe and in my book that means anyone can look up in to the sky, aim their totem at it, and go to it.
Yep, that’s pretty much how I think most people would set up their planets. I would, anyway.
If you’re curious, here’s the poll. So far, like I predicted, anyone can visit the planets of those that voted.
dont Unbeacon…but rather make a new beacon (small area) adjacent to your town…dismantle expensive blocks, tech, and materials and store in the small beacon. Then delete the town’s beacon when finished. This way youll have a stock of materials for later to get you going.
then try mailing works wonders for me all week
I don’t have the heart to ask someone to remove their builds for me, especially since they have done no wrong doings. Besides, there will be someone else doing it instead cause I do not have the plots.
Hence why I want private worlds so that I can build in peace. I just want the option to build freely in this game without disturbing others or getting disturbed. Is that too much to ask from a game like this?
nope rented world are allready confirmed
Really? Damn, that gets my hopes up! Best news all day!
It’s been confirmed for a long time.
We just don’t know the ‘when’.