[Dallas59]

Or maybe they don’t contact us because they just don’t care?

[The Magical Mischief Tour]

http://en.wikipedia.org/wiki/Zoo_hypothesis

[Smokin' Joe]

Don’t worry. The really big rocks are on the way...

[MHGinTN]

Or maybe they don't want to be directly involved with such a primitive species. They've been exploiting the resources of our solar system for a very long time. Why bring spoiled brats into the family of intelligent beings when we have yet to demonstrate that we are 'intelligent beings' in the sense the alien races regard that characteristic?

Imagine how fast the disease of our species arrogance would spread to the universe, if we had the capability to step in and out of volumetric time, to traverse the expanses almost instantaneously! We would be the disease all other races had to fight against which would corrode their civilizations into squabbling hordes. Better to keep us quarantined for now.