See my answer above. It comes down to the filibuster. That's a procedural rule making it so that the Democrats do not, in fact, currently have control. They have to find 10 Republicans to "come across the aisle" in order to get legislation on the floor for a vote. Getting those Senators to come across the aisle is known as politicking. That's just the way the system works.
Democrats do have the power to change those procedural rules, but there's huge downsides in doing so.
Bottom line - don't look for easy solutions to complex political problems. They're likely to be loaded with unintended consequences.
So the question remains - why don't they just do what the court has said they should, and pass a law?