The OP is essentially playing into the AC business strategy of souring the milk of the upgrade scheme, lowering the prices of Z fares, and having people buy directly into the J cabin to avoid uncertainty and frustration.

Reflecting on my days as E, I used to happily buy up to Lat fares on those routes where an upgrade was important, and several people here have said the same.

So I'm not sure how much this new tactic is changing the amount of revenue generation for AC (particularly considering how often Z<Y/B), except that clearly loyalty is being chipped away slowly, and no substitution for lounge passes, free meals in Y, etc.etc.etc. will change that.

Certainly any paid international J I buy has not been on AC this year. I either pays my money and takes my chances in T+ with eups, or enter the market of discount business fares as a free agent