Historically, the preliminary inquiry was held to allow for the disclosure of evidence, but now, given the rules surrounding the disclosure of evidence handed down by the Supreme Court of Canada, it is no longer important in that regard. However, the preliminary inquiry is important in another way, as mentioned by the president of the Bar, and that is to encourage guilty pleas.
The preliminary inquiry had its raison d'être, and that historical reason may not exist any longer, but there are other reasons to keep it.