It might be a strange thing to say for a porn game but the Lust mechanic -at least the way it is now- is almost useless.
In the old game it at least had a function for unlocking specific traits but here the only use I could find it having is in combination with the Succubus class for easy XP farming. 

It does not seem to influence prostitution jobs or traits in any way otherwise and even if it might have an effect on the interaction menu (read things like starting aroused or sth) that isn't all that useful either, given how -even without special wearables- all characters accumulate lust over time anyway and how -given enough characters- that will inevitably outstrip the number of available interactions per week anyway. Further it can be ignored as there are no negative side effects from not taking care of it. Doing so also would waste time for characters specialised for other things. 

I think the general idea makes sense but so far there hasn't been any meaningful functionality or mini-events attached to it. Like characters jumping the player character when left at too high lust in the old game. 

What would be nice would be a relationship between the lust stat and the wit stat or combat abilities inducing lust in enemy mages to lower their MATK, maybe an equivalent for the succubus class to the leadership skill fear aura.  Or sth like a maxed lust stat unlocking a new option in dating to ask to try new things that progresses the deviancy level or nullifies any penalty for them for any sex interaction started from that dating screen.

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Another thing that would be great would be an alternative way to increase rank to the sacrificial one. 
Oh and another thing that had me very confused until I scanned the dialogue files. The dialogue for getting Jean from the mage-guild is still left in so I was wondering for a while what I did wrong until I figured out that now she's acquired after Act 3(?) . Does that mean there's a way to still get her before act 3 or would that mean too much work for a branching narrative and therefore the left in dialogue just be a leftover?