Played 4 hours of the Steam Demo. Intrigued by what I've seen so far. I feel like I have a fairly solid grasp of what's going on and some potential improvements.
Monster Girl Exploration: Having the Monster Girls utilize aspects of their progenitors to aid in exploration and resource gathering would be a neat usage for them.
No Monster Girl Double-up: This hasn't happened to me yet, but I've been struggling to keep from doubling up on my Monster Girls. Having a mechanic to prevent that would be nice. Don't really need two snake daughters.
Turn Debuffs into Buffs: I had a thought, and it's not likely to be useful for the sake of game balance, but the debuffs that effect character appearance (Sticky, Smelly, Parasite, Tentacle), were, in my honest opinion, rather negligible. I just have them and keep them. Makes the enemy waste their turn applying them. So having a mid-to-late game method of turning those debuffs into buffs would be something I'd like to see in the sequel.
Weapons & Armor: The idea of having to "repair" your clothing is a neat idea, but I often left it alone. Similar to the Debuffs, the stat changes weren't that big a deal compared to just dealing with it. The weapons were a nice touch, being crafted of each breed's progenitor, but instead of "Mod" for the Monster Girls, maybe make it actual weapons. Like, Snek gets a blade for her tail, Scorpion gets a pair of large claws. Something to that effect. And, perhaps, let them use the Player Weapon made of their progenitor monster (snek uses snek gun, Mosky uses Mosky gun, etc).
Space Combat: IDK why, but I only had the port-side cannon able to load and fire at enemies. Might have been a bug. Otherwise, I'd say to let some of the Monster Girls/"Recruitable" party members handle things like reloading, shield recharge, and basic repairs (putting out fires, fending off tentacle monsters). Additional uses outside of the main turn-based combat would be a huge help.