They aren't telling us because they are warm little buddies. They are telling us because the government or just ourselves have pissed them off, or they see us as ants to smother and pour molten silver or copper into our ant hills. All our desire to meet other beings may be our end. So they tell us, and as all science fiction writers write except for a few, that we always survive to conquer our invaders and then go to their planets to annihilate them.

But some writers have shown us that we are nothing but the learning arm and thoughts of some minor god and will fade away at their whims.