I have no doubt that in many cases these revolutions have resulted in potentially worse individuals coming to power. I also know from history that many of America's worst enemies are individuals that had previously been friendly to us, who were given money, weapons, or technology to 'help' us out, and then later turned using our own resources agianst us.
This long pre-dates Obama as does the violence and conflict in the middle east.
With the exception of Libya and Syria, the US' involvement in the collapse of dictators has largely been very minor until it was apparent the dictator was on the way out anyways. Once is was clear the Mubarak wasn't going to stay in power we had little choice but to pretend that is what we wanted. The fact is once these governments were about to be toppled Russia, Iran, China, etc. were all looking to get involved and to try to shape the new government in a way that was most favorable to them. I do not believe it would have been in our best interest to sit on the sidelines and watch.
Had we done nothing, how might the outcome have differed?