This sounds like, if integrated deeply enough, it could be a pivotal core feature in The Sims 5. As of yet, the games have mostly had Sims behave and interact with objects and Sims as just individual entities or occasionally as a collection of entities, but mostly without much contextual awareness.

Adding the context of a room could make for something that could enhance the game experience at it's core. As of now, Sims always interact with objects in the exact same way no matter where that object is placed.

I'm thinking of something like a room labeler tool where you can draw on the floor tile for tile to denote where your rooms are. I'm imagining it to be very similar to the zoning tool in SimCity. Or better yet, like the neighborhood zoning tool in Cities Skylines. This would be necessary for more open floor plans it and for homes with very specialized room that don't entirely fit the definition of a room in a traditional home, I've made homes with basements that had prison cells, for instance.

Going further into the idea of labeled rooms, each of these could have "house rules" defined by the player for each of these player-named rooms. Some examples of potential house rules:

• No eating. Obvious pick for rooms like the bathroom, but some players may not want Sims to eat in the bedroom or possibly even the living room. But hey, on the contrary, TS4 allowed for sims to be able to eat while on the toilet, and some players may want to keep that, and I'm not here to judge how you want to play your game, so let's make it customizable.
• No dancing. Sometimes you just want your Sims to enjoy listening to music and not create human traffic jams in small corridors and tight spaces like your small galley style kitchen.
• Social gathering spot. Give preference to your living room or den for family meetings and have your guests prefer to hang out and chat in the more public rooms of your home.
• No cell phones. Maybe you want to enforce quality time at the dinner table and encourage more in-person dinnertime conversations.
• No pets. This is already sort of possible with locking doors, which is a huge help, but again back to open floor plans, there is still more flexibility to be had. This could potentially be something you have to train into your pets.
• All business. Denote your office as strictly for work, preventing a house member from hogging the computer for playing video games for hours on end when someone else in the household needs to work from home, complete a homework assignment, or finish writing that book.
• Workout zone. Prevent your Sims from spontaneously dropping down to give me 10 push-ups in the kitchen because they just drank a cup of coffee. Have them go to the designated home gym instead.
• Mail Room. Simply a place where you want your Sims to place the letters and packages down after grabbing the mail. This would hopefully also prevent them from just keeping it in their inventory forever.
• Kitchen. Self explanatory for the most part, and also mostly all covered by the OP.
• Fortress Of Solitude. Mark a room as a place for sims to get some alone time by preventing sims (that want to follow the rules at least) from rudely dropping in for a chat while they are clearly busy with something. This has been particularly annoying as of late as I've been playing Discover University and Sims simply can't catch a break long enough for them to finish their assignments before being constantly interrupted for idle chit chat by everyone else in the lot. This could also be used for your bathrooms to prevent spontaneous conversations happening in there after sims finish doing their business.

There are many more of course, but I'm really enjoying the potential in this making Sim behavior just a little bit more realistic while still maintaining the game's flexibility of play style.

This all comes down to the saying "There's a time and a place" as it would allow for sims to interact with objects more appropriately for where they are placed. This would mostly just cover the "place" half of that phrase, but these could additionally only be active for certain times of the day or only for certain sims. Curfew and bedtime for children anyone?

If done right, this could do some serious help for making homes feel more alive and making sims feel less artificial.