Medical "insurance" is generally not insurance, though. Well, it is, but it's a bastardization - a maintenance plan + insurance, kind of like like whole life (savings account + insurance).
Reassessing your risk, is not cheating you out of past premiums. Premiums (in the theoretical perfectly efficient market) are in the now and based on current risk for the term of the policy. It's that probability thing that people just don't get. Changing risk pools *should* be associated with your actual risk. You begin every year as a new assessment, and you end every year with a sunk cost. It's a die roll, and if it comes up snake eyes, you "win" restitution; if it doesn't you "win" by not having some tragedy befall you. Either way, you place your chips and roll the dice; but at the end of the round you can get up and leave.
The ACA changes the rules because healthcare, 51% of us have determined, should be different. So the range of premiums is compressed, and the healthcare cos must always keep the table open for you if you have chips to play. But for everything else, it's just another table game with the house favored by a few percent and a bankroll large enough to weather a bad run of dice.