Yes, I know that kitchen comes from cucina. I got the etymology down very nicely. My point (and I do have one) is this:
Bedroom - room where your bed is
Bathroom - room where your bath is
Living room - room where you do your “living” (and why isn’t it one word?)
Dining room - room where you dine
This could go on and on and on (Ballroom, drawing room, family room, rumpus room, laundry room, great hall, entry way, etc etc etc). All are descriptive terms. Someone new to the english language who knows the word “room” could pretty easily surmise the purpose of most of these rooms if they were familiar with the preceding term. The freak terms is kitchen - Why not cooking room? I leave out library and pantry because they are also commonly referred to as Reading room and Store room.
Anyway, if anyone has any insight into why the language developed this way, I would be fascinated. Yes, these are the kinds of questions that keep me awake all night. Yes, I need to get out more.
As you are aware from the etymology, in its day, kitchen meant cooking room. It still does, but we do not pronounce cook the same way. Take a look at when these words came about. I think you will find that words such as hall and kitchen are much older (e.g. 12th century) than bedroom, living room and dining room, which are relatively modern (17th century and up). Since kitchen was already established, there was no interest in replacing it with cooking room.
Ah, but room is one of the older words, so why was cooking room not created way back? Room took a while to take on its archetectural meaning – way back it was more along the lines of open space, a more outdoor concept. When room started regularly being used in the archetectural sense, it started getting combined with purposes, to give us your list of rooms.