Why wait? Because if aliens, as hyperadvanced as they are can clearly see that if we announced contact with alien life we would do like we always do.
The pilgrims are an excellent example, and now, I shall alienize it, so to speak.
Alien: Hi, we're from a galactic federation that wishes to help you into this new world (space). We will show you how to survive and thrive in this
Human: Thanks, that's a big help. Space is cold (like winters in north am), and we have no real idea what we're doing in this strange and foreign land
Alien: It's all good. Here, let us show you how to terraform planets and other stellar bodies (farming) so you can draw the resources you need to
survive this new world (space).
So we learn, and not too long later....
Humans: Well, we know how it's done now. Let's just conquer the whole damn galaxy and take all the resources we need. We got all their ideas and now,
since the one thing we're good at is weaponizing, we've built weapons that make the stuff they got look like a bow and arrow.
Aliens: But we showed you how to survive! We could've let you die in the cold winter (space)! Why would you do this!?
Humans: Hey buddy, it's what we do. Better just take it, else wise we'll make to where the only power you wield in the cosmos is a casino.
That's why advanced aliens don't open up to us. Because they know better.
edit on 5-5-2012 by Lasr1oftheJedi because: (no reason