Writing for The Weekly Standard, Jay Cost identifies a problem both parties have with their presidential nominating processes. The current process is ill-designed to produce "fusion" or compromise candidates broadly acceptable to all factions within the party.
Instead, it tends to select an individual well-beloved by one faction and possibly barely tolerable to another. As Cost points out, this makes post-election governing much more difficult.
Cost does a good job of pointing to a problem and establishing its relevance. He totally drops the ball when it comes to proposing solutions. Perhaps he can think of none. I know I can't, off-hand.
Nobody, I hope, suggests a return to the days of smoke-filled rooms of party professionals horse trading to identify a candidate. It was no better, and sometimes worse.
