ETs have not made contact with us because we are not ready, reflect on yourself and reflect on society, why would an advanced alien being want to contact us now? we need to change our ways, but we're almost there.
as for the government covering this up they may be, then again they may not be. i see 1 of 2 possible solutions:
1 - the government is trying their hardest to keep us from knowing so they can keep power, if we know they exist we challenge everything we know, including our society
2 - the government is slowly preparing us for disclosure, and will use the information to disinform us into thinking they're here for bad reasons in order to take complete power.
personally the 2nd one makes more sense to me as i see more and more space based entertainment, it's a pattern that i've been following, take a look for yourself, it's everywhere.
that's what i believe, but i think these aliens (not all of them, but most) are here for good, or neutral reasons, some being bad, but i'm sure the good and neutral are restricting them from doing harm. then again i could be wrong. but it looks as if we will have to just ride it out and see what happens, should be an interesting year.