In general the West is not the same as Russia, they can't do things on the foreign stage while ignoring the public backlash for long periods of time anymore. Russia do not have these restraints; it uses foreign issues to distract it's populace and is largely undemocratic.
Also, I do not know what you mean by "shouldn't be possible", as there was nothing really stopping it. Misinformation is pretty much always apparent in elections, but this time it was done by racists, trolls, and foreign government on a medium we all do not want to be monitored heavily (internet). Our media also caused this with their focus on Trump's actions rather than Hillary's policies, not just Russian government actions.
You are also incorrect on your thoughts that U.S can't dictate many geopolitical agendas. It can, but Democrats in general tend to be more reactionary on global politics, preferring to find other routes or lead task forces and other such organizations rather than just go in unilaterally. Issue with that approach, is many nations have different agendas and many do not have the desire or means to share the workload.
Putin isn't smart, his opponents are just more restrained for moral and political reasons than he is and that is a good thing, but as you can see it has major disadvantages.
Fine.
But, In my opinion the role and the position of the west after 8 years of this President are in a much weaker position than before, the last huge and unthinkable event, the summit between Iran, Russia and Turkey for the shaping of the future of Syria, without any western country is something totally new in modern history.
I'm absolutely curious too see the western reactions to this, how they will sell it to their public opinion and how they are going to retaliate.
I don't know if people understand how big this is, it changes the whole world geopolitical equilibrium.
Russia for the first time got a stronghold on the middle east, this means Mediterranean access, gas and oil control over the region by a Nation that already has a central role in the energy distribution, means that the Shia Iran got a huge role in region for the first time as well, this means the fall from grace of the USA Arabia axes that ruled the region till the ww2.
It's something that may change our future for the next 50 years if not challenged fast.
And be wary of the Egypt swinging.
Also sorry,but i can't, by any means, follow you on morality of the west in applying their agendas is just naive and doesn't have any place in the execution of geopolitical targets.
Public opinion was, is and will be moved by propaganda in the west as much in the east if needed.