Manually join another player's instance

[Twinsoul]

Why would they put the time, money and effort in making a feature that would not stay for a long time?

Just because it's temporary is no reason to do a shoddy job. Folk should really have higher standards for a world-class development company like this. No matter what people think of the budget SE gives this game's devs, it's not like it's being made on an indie game's budget. They can make a functional UI.