The way it is currently scheduled it will be the same old same old scripted Q&A. The way I am suggesting, it would be real debates. The candidates would be given topics to debate or would agree on the topics and would flip a coin to see who went first. They could ask each other questions or ask each other for clarification on this or that, but there would be no moderator with the usual 'gotcha' questions and who avoids anything that would allow the candidates to shine. There would only be a panel of objective judges to judge the debate and rule on a winner and a referee who would not participate or ask questions but would be the time keeper to ensure each candidate got equal time. Maybe each candidate in the debate could choose a couple of topics to address to make sure each candidate could choose the issue in his/her platform that s/he cared the most about.
I am guessing that CSpan would jump at the chance to host the debates and could probably furnish the objective judges to judge them.
Still a terrible idea in terms of doing it during election season. Where your idea would work is in an off-year. Intelligence Squared often does this on NPR already come to think of it.
But if you have 16 candidates, you're scheduling 15 debates to determine a "winner" who may or may not be the leading delegate winner on the ground.
The error you are making--and it's a pretty serious one--is that you are equating success in debates to success on the ground. Winning an election is much more complex. All politics are local. If you like Candidate X's answer on immigration vs. the "winner", Candidate X will probably do well in Texas where immigration is a bigger issue than it is in Florida or North Carolina. There is also the favorite son vote, soft money ads, etc...