I strongly believe that only members of a political party should be eligible to vote for the order of candidates on a list.
Active members of a political party are responsible for determining the spirit and direction of a party. The one single tangible benefit of being a member of a political party is this vote.
This benefit should be maintained. A functioning democracy requires members of the public to join and participate in political parties.
I believe it would be wrong to throw this open to the public so that all voters have a right to determine the order of candidates on a list.
In this instance, the part's perception of a candidate's suitability is more important than the general public's perception.