Well one can't argue with that, literally.
But there is no right to do so, and for very good reasons that make the US the only country to mostly publicize nominations. Parties are not public associations. They are not constitutional or even legal functions of government.
A nomination is a proposal. We, Democrats, propose that this person be president or we, Republicans, propose this person. There is no right for anybody to tell them what to do. They have a right to association and determine their own values. Voter choice in November will determine whether that was a wise choice or not.
Now as we have seen, the greatest presidents in history, the founding fathers, Lincoln, Teddy Roosevelt, FDR, Johnson, all came from smoke filled rooms. What have we gotten since 1976? Mediocrity at best.
The reason? Demagoguery mostly, and that primaries tend to bring out the crazies that politicians are so afraid of and not in a good way. I would argue this has been mostly a force for evil on the GOP side. We can't even get SCOTUS hearings because the moment one senator caves - ooop - primary challenge from the Tea Party. We really don't need that to happen on the Democratic side.