You don't need to ruin your game to make money. Just make spending money a lot more EXCITING.
The best free-to-play games make playing for free super fun, and make spending money even more fun.
It is not that hard.
1)Be generous with your hard currency, but give players a bunch of good reasons to spend a little every day. Usually this involves a ramping up of some cost.... like say epic pachinko or energy refill starts cheap but goes up the more you use it.
2) Give plenty of incentives BESIDES kabans for making purchases. Since you are generous with cash currency it loses some value, but you can get the value back by putting events in. Like any purchase comes with energy refills. Purchase of X amount this week gives you an exclusive girl. VIP level can be effective too (permanent bonuses from making purchases).
3) Quests, Quests, Quests. Put in daily tasks like gain 50 affection (and 100, 500, 1000). Use epic pachinko 1 time, 5 times, 10 times. Refill energy for kabans 1 time, 5 times, 10 times. People find themselves wanting to finish these quests and spending money just makes sense because you will get a free girl this week anyway.
The current direction seems to be "only people spending money should be having fun", but that will only kill your game. Please change course! With a few changes you can have people happily handing over their money, while giving them plenty of free players to play against.