Personally, I think that a truly equal household would contain two dens, a His & Hers solution. It is nice to have a personal space to retreat to, particularly to pursue interests that the other party might not be interested in. Of course, if there is no basic tolerance for His model aeroplane tinkering, or for her novel writing, then the household is jolly well buckling on poor foundations as it is.
Just because you are having a joint household together, does not mean that you will, or should, osmosis together into a united whole on every front. A husband and wife will always remain two different individuals, but closely together. Being blind to that fact will simply create a bubble of resentment and anger that will do much more damage to the relationship than any of His guitar practice, or any of Her pottery, could ever hope to do.
The lady of the household tends to be in control of its appearance, and that is one of the main reason for there being some sort of man-reservation. If that is a mutual agreement, one that is not a source of resentment but simply how the household is divided as suits both, it is not a problem. It is, however, a problem when the well-being of the husband (or wife) is less important than the décor and ambience of the house. Further, if it is so appaling that the significant other wants some time on their own, then I dare state that the relationship is not in very good health as it is, and taking away His stupid model railway, or Her stupid knitwork, by annexing the space they are done in, will not accomplish anything. It will not remove a time-sink and tie them closer together again, but will strengthen the want and need to get away from it all.
I belted the ravings above out because it does make be rather sad and angry that basic tolerance for another individual's fancies and interests is so often portrayed as optional in marriage and relationships...