I mean, unless its changed recently you still can't fully customize your character. The transformation system is super restrictive in a lot of ways. I like being able to fully customize a character exactly how I want them, even in ways the game doesn't currently allow by using transformative items. That's the biggest use of a cheat menu for me.
Also, I like being able to enable specific perks if I want to start with a more interesting character. And modify the effects of those perks, because that can add some pretty fun chaos into the game. And change how all the pregnancy timers in the game work. Specifically, I want to create a way to jump from one pregnancy stage event to the next to speed up how quickly they take place, but without causing them all to trigger at once like happens modifying the speeds now. I also like essentially creating a fast mode for grindy activities. It makes it quicker to gain stat increases and exp through grinding without eliminating them entirely. And about a dozen other things I like tweaking with the game.
The cheat menu in the game is pretty good, but there's so much more the game engine can do that isn't supported in game. But if you make those changes directly, the game engine supports them without any issues.
Plus like, it'd be nice to add all the cut content back into the game.