I dropped the game myself for similar reasons. I was going to write a big review on my experiences but I'll try to sum it up in a shorter format.

I like how the combat works, the idea of upgrading and collecting various characters, and swapping them in and out of battle as needed.

What I don't like is how long everything takes to max out, and how they keep repeatedly nerfing drops as you mentioned. I know its soft launch and there's a lot of balancing going on, but I'm not giving them the benefit of the doubt for one major reason. There's a reason this version is so different from the Taiwanese/English and Japanese versions.

Apparently the Taiwanese version of the game failed to make enough money and its servers went down. This studio bought the rights and assets for the game, slapped on a new name and worked in a new plot to make it an H game. They also stripped out almost all of the freebies from the other two versions, and made it so there are only 4 1* girls you can farm quests to upgrade. Sure, you can still get everything in the game free technically, just expect it to take 6 months to max out a girl. That's far too long just to unlock the ability to have a 7* girl naked in her idle pose for me.

They took a game that failed and made it worse. So yeah, I'm not spending any more time on this one.