Planets take billions of years to form. They do not just appear. If Admin has already designed the planets and know where they are going to be placed then why have they not already positioned all of them? The thought of having a planet pop up in territory I just left after searching it is disturbing.
We position them in random intervals because it would be impossible to add them all at once. There's thousands and thousands of potential planets. Adding them all at once would take infinitely more time than the administration has to give.
Adding them in as we go along makes it easier on us, and ensure that we'll have planets to go around for years to come.
You don't have to own a planet/find one. Under the old galaxy what we had was what you had to work with, anything after the fact is now butter.