A very short answer.
The overwhelming support for the “Magnitskiy Bill” shows that there is a considerable non-partisan majority in Congress that believes that Russia is an exception to normal rules: trade with Russia yes, but never without conditions.
The USA is lost to rational considerations in this respect; for Americans Russia is both the Eternal Enemy and The Brother Who Won’t Listen to Good Advice.
To Americans in power, that is: to ordinary Americans, Russia hardly signifies in the reality of unemployment and food stamps.
The opportunity that opened in 1991 has been squandered: Washington, and we who follow its lead, have taken another step to create an enemy. And at a time when we do not need any more than we already have.