If a man puts on a dress he does not become a woman--not even if he includes all the details right down to the lacy undies. No matter the quality of his disguise, his lack of genuine femininity renders him unsuited to serve as a representative for females.
Open primary voting allows for the same distortion of reality. As long as presidential nominees are selected by parties, only the members of those parties ought to have a say in selecting the nominee. Abuse of an open system is going to happen, with voters trying to swing the opposition party's vote in their own party's favor. However, the greater threat lies in the more subtle impact of allowing voters who lie in some undefined middle ground between the Democratic and Republican parties to influence the course of any group with whom they share no affiliation.
The argument that open primaries increase voter turnout has no validity to those of us who adhere to a specific party and embrace a certain set of political principles, only to have those principles altered by those outside the party.
Those voters who truly cannot decide between the two major parties and feel compelled by conscience to register as Independents ought to pour their political fervor into putting forth stronger third party candidates who most fully represent their ideals. If they lack the interest or inclination to do so, that is so much more reason for them to abstain from primary elections.