I hope you are talking primary races only.But then again, it should be wrong for a Democrat to vote for a Republican in a primary, then vote for the Democrat in the general election. That is why my state has a primary for either party. To me, if you register as a Democrat, you vote Democrat unless you wish to change your affiliation before hand, likewise with Republicans. There should be an even playing field for both candidates, with no ability for one party to vote for the other. You are essentially cancelling out the votes of the other party when you are voting in THEIR PRIMARY.
You can create a registry for either party, and work from there. Nothing is impossible to enforce if enough effort and forethought is applied.
I would oppose any restriction that would allow Me to vote for a Democrat who had better values than the Republican in the race, simply because I was once registered GOP.
I am. I would not extend that to general elections. But a party should be able to choose its own nominees without interference from the other party. The law should reflect that.
You're describing closed primaries - which most states have.
But the Constitution pretty clearly gives control over elections to the states, and Mississippi chose to do it differently.