We have propped up dictators (Diem, the Shah, Pinochet); We have tried to overthrow foreign leaders (Noriega, Fidel Castro); We have promoted "regime change" (Assad, Hussein). We have also tried to influence democratic elections on many occasions-- Obama tried to help Ehud Barak in his anti-Netanyahu efforts, and Trump has tried to help Netanyahu.... Some with aid, some with electioneering. There are many other examples. This seems to be a common element of American Foreign policy, regardless of whether the occupant of the White House is a Democrat or a Republican.
So, why are we so upset that the Russians were trying to do the same thing?
I think it is reasonable and understandable to be upset when ANY foreign entity interferes with your election results but the hypocrisy of it all when US foreign policy conducts it on a routine basis, whoever the incumbent or sitting president, is pretty rich.
First, we try to bribe them. If that doesn't work, they we clandestinely support the election of the opposition who hopefully will be in toe with our interests. If that doesn't work, then we arm the opposition and instigate a coup. If that doesn't work, then we declare they are harboring terrorists and-or chemical weapons and bomb the place to oblivion. Then, we go in, rebuild and make sure the next government plays our tune.
Works like a charm most of the time