Not all existing wall openings are desirable. If you're an art collector, for example, you'll want space to house your collection. If there are two entrances to a hall where only one is needed, you can extend the wall by closing in the space, stretching the usefulness and enjoyment of an adjoining room.
While some walls may inhibit the openness, light, and view of a space, a lack of walls may limit your ability to feel embraced and cozy in a space, bookcases within reach. A room with too many wall openings is unsettling, far from intimate and inviting. A room with openings on all four walls is not a private space but a public hall. Don't let preexisting wall openings intimidate you. Be opportunistic in exploring ways to literally extend your wall space; whether you want to close in an opening for more privacy or to provide space for wall art, books, or collections. Invariably you will find wall openings that you really don't need, where you could use the valuable wall space for storage, art, books, or a furniture grouping and architectural embellishments.
Why have two doors bunched in a corner, one leading from the hall, and another from the kitchen, when one is all that is required? Remove the doorframe and door, close the wall with sheetrock, tape the seams, spackle, and paint. Now you have new wall space in both rooms, providing a place for a standing desk or bookcases in the library, and a wine rack or even an additional counter in the kitchen.