Yes, it is very much possible to play it obedience only, I do it every time I play. The girls losing Love when you force them to do something through Obedience is exactly what you're saying that is not in the game. They go against what they want all the time, and as someone said a few pages ago, when they have high enough obedience and you penetrate them without their consent (which is rape) they just close their eyes and accept what is happening. If that's not "going against their own free will" I don't know what is.You are really making it out much darker than the narrative intends it to be.
The game mechanics still show completely independent thought on the girls part.
There is no point in the game where the girls completely go against their own free will because of addiction.
The entire obedience stat is played off as a sexual fantasy,not actual mindcontrol.
In fact...I dont think its even possible to interact sexually without the love stat(which itself decreases constantly if the MC behaves like an ass),though someone who tested that would have to chime in.
Like I said,I just dont see it and I think you are setting yourself up for disappointment if you expect the story go anywhere but a silly romcom.
This game is already very dark, and even the Love route is mostly abusive given the addiction thing. Adding any of my suggestions wouldn't be a stretch at all.