It was never meant to do anything but punish Russia for being 'naughty' in Ukraine. It was geopolitical chess being played by novices, and they predictably screwed everything up.
The original goal was to counterbalance Russia. That started with NATO expansion dozens of years ago, which Kennan rightly criticized as completely counterproductive and unnecessary. This eventually promoted a backlash when we took it too far (to the point where Russia had a lot to lose, and we didn't have the will to actually back our sabre-rattling up with anything substantial). Russia incited violence in South Ossetia and Donetsk, then seized the Crimea and the Black Fleet base in Sevastopol, as they had yet to complete construction of their new base in Novorossiysk when movements towards Europe were made by Ukraine. Russia only really possesses access to warm water points in East Prussia, the Black Sea, and the Far East. They lease a base in Tartus, Syria, making the country vital to Russian interests as this is the only base outside of a NATO-controlled choke point (Bosporus and Dardanelles or Straits of Denmark) in the West. So, the basic thinking is that we would 'punish' Russia' by funding rebels in Syria to overthrow Assad. This failed for the same reason that NATO expansion did: the policy makers were looking at things from a non-realist perspective. Russia is a rational actor, they had much more to lose here than we did, they KNEW that they had more to lose, and they knew that we knew, so they called the bluff, and now Syria is a nightmare, Europe is being destabilized in a large part by the refugee crisis (which benefits Putin, herp derp Hillary). Now the entire region is a mess, with conflicting interests between Turkey, Russia, Iran, and Israel, and we're sitting in the middle dumbfounded. We will have egg on our face if we make the correct move (what Trump proposes), but we need to do it anyway, and use recognition of Russian control of Crimea as a bargaining chip. Russia has no interest in annexing Donetsk, so we also have a chance to resolve that conflict and try to return things as close to the status quo ante as possible. The hardest part will be restoring the balance of power in the Middle East, as the Kurdish problem will be difficult to deal with, which will distract and destabilize Turkey at a time when they ought to be acting as a strong firewall against Russian influence. They share an ethnic group but are comprised of three different polities, all of which have divergent goals and methods, and none of which can be 'put back into the bag' at this point. And we have to manage alllll of this while pivoting to China and trying to manage the brewing conflicts in South Asia.