WaltonGOP, being unregistered with any particular party, I might fall into that category of wanting to vote in a party. Sure, I could sign up with a party back in December, but what if I didn't know which candidate I liked the most by the end of Dec. Since the vote isn't until Jan 29, I don't know why I couldn't join the party all the way up until I pull the lever (push the button) for the candidate of my choice. Today, many people are unregistered with a party, because they don't agree with either the Dem or Rep parties as a whole. Also, there are many candidates dressed in red, who are really blue, and the opposite might be said, too, though I don't personally see that today. I think the more important part of fairness is having only one vote.
Problems with the system would play a major role this particular election. With Florida and MI delegates not being seated for their votes, due to the changing of the date of their primaries, I could see all of the Democrats voting in the GOP race, since their vote for Dem wouldn't count anyway, due to the DNC not seating the FL delegates, and the delegates and superdelegates votes are the only ones which count for electing the nominee. They would likely strategize to select a week candidate to screw up the race for the GOP. It would be poliTRICKS at its finest moment.