Not only were most of them unelectable, but they were pseudo-conservatives (i.e. conservative rhetoric on some hot-button issue, establishment on all others). Cases in point: Rick Santorum and Mike Huckabee. They sound "far right" on social issues, but on economic issues they were probably more liberal than Romney. Another example (and an even bigger clown than Rick or Huck) was perennial candidate Alan Keyes, who supported affirmative action and slavery reparations.
That is why I said “too many non-establishment candidates”, and not “too many conservative candidates”. I couldn’t bring myself to call idiots like Santorum and Huckabee “conservative”. But “non-establishment” is, as you point out, also incorrect. Maybe these candidates defy any label other than “unelectable”?