A dictator backed by US gets toppled by his own citizens. Typical response from US government is to support dictator to the last possible moment. If it does not help, US politicians with their mouths full of lies about "democracy and freedom" attempt to reinstall the old regime with another frontman. This scenario played well in Egypt. In Libya, US and EU did much worse things: old dictator has been removed and whole country has been pushed into permanent civil war.
Your comment is unfair to the U.S. government.
In one breath, you criticize the U.S. for supporting friendly dictatorial regimes. In another, you criticize it for supporting popular rebellions. What is the U.S. supposed to do? You accuse the U.S. of committing atrocities in Libya, but it neither sent ground troops nor war-planes beyond those providing logistical support to allies.
As you mention, the outcomes in those countries that have cast off dictators have not been good, but that can't be blamed on foreign powers–they stayed out of the nation building process. If you are going to blame them for not attempting nation building, I point you at the cautionary tales of Afghanistan and Iraq.
We don't hear nor see anything about it because of media blackout instated by fucking corporate media.
If you believe that there were atrocities committed by the U.S. in Libya, please be more specific. Preferably cite reliable sources (there are other sources than corporate ones). If there were atrocities, they certainly weren't large-scale. The U.S. military doesn't have sufficient information security to keep large scale atrocities from becoming public. Certainly not the murder of 1500K Libyans are you are implying. If you can't be more specific, STFU.
The lack of success in achieving stable democracies in the middle east and central asia obviously has far greater factors than foreign involvement. The lingering effects of colonialism obviously play a role, but other parts of the world have been able to bounce back from colonialism (East Asia and South America are examples). The inequality bred by a large economic dependence on extractive industries (mining in particular) is a better candidate. The failure of West and Southern Africa to achieve stable, equitable societies supports this factor as explaining middle eastern stability. Of course, there are likely cultural issues involved as well, the extremism of Salafist Islam and the general misogyny do not support peaceful, democratic social ends.
And we still perceive ourselves as being "good" except that we are no better than nazis were. Just our warmongering elites learned that masquerading killing with crap about "democracy" and "freedom" is better than being explicit and grotesque as Hitler was. This is propably the greatest mass hipocrisy excercise in history...
Of course, the motives nor methods of the U.S. nor its allies are beyond reproach. There certainly have been many atrocities committed by U.S. forces. There have also been many interventions undertaken for nefarious purposes. However, there have been several undertaken for reasonable humanitarian purposes. Furthermore, if any nations that does not want the U.S., U.N., or other stable Western democracies to intervene militarily can simply adopt a stable, peaceful democracy.