The American people do have a say, most just don't want to exercise their right to have that "say". Yesterday, every adult citizen (with some shameful exceptions e.g. soldiers) of Iowa had the chance to have their "say" about who they wanted to be the candidates for president. Only a tiny minority used this opportunity to have input into the selection process. Whether there really is only 400 or so Iowans who support Duncan Hunter will never be known. That's how many put out the effort to vote for him. Real preferences for other candidates is likewise unknowable.
The majority of U.S. citizens appear to be quite comfortable with letting others choose for them who will be the candidates. No matter what selection system exists is of little concern to the majority because they choose not to take part in the process.
We, collectively, get what we deserve.
I'm sure Marx would have agreed with that.