Personally, I think character building and development, is something that brings quite a bit of fun, and is a differentiating factor for your game. It makes it so that even the objectively existing flaws in the current state of the game (such as repetitive scenes or a miniature sandbox), don't detract from the gameplay.
Regarding the tree or alternative forms of character development, in my opinion the fact that we are dealing with a pornographic game is not a disabling factor. Because, further stages of character development could, for example, unlock further animations, fetishes or progress to further levels of perversion.
Obviously, these are very preliminary thoughts, but they are based on one thought pertaining to the game. And that is that I believe that each new update should mean more options in character development. This could, for example, be correlated with new activities, which would mean a higher difficulty level.
Because, in my opinion, a situation in which we are faced with Lily/Claire/Jamie with totally doped-up stats who easily get, the highest score undermines the strongest aspect of the playability of the game.
And to conclude, I am aware of the limited resurgence, and don't take this as a criticism because it still must be pointed out, that there is highly unique aspects, in this game.