I admire people who do the unconventional. Just because the world says something should be one way, does not always mean it's the right way. One place that I notice that most people tend be reluctant to "buck the conventional" is in our homes and more pointedly in the formal dining room. The least used room in most modern homes is that formal dining room.
Don't get me wrong, I love and regularly use my formal dining room. I have a china cabinet filled with Royal Albert china and a cabinet with English teacups. We eat in that room whenever we have company, and when I cook Sunday dinner for our family. I would really miss my formal dining room. But I am in plenty of homes where this room is used a couple times a year and the rest of the year it just gathers dust. Meanwhile the home owner struggles to find enough space in the rest of the house for other activities. This is heresy for an organizer!
If you have a formal dining area and are short of space in your home consider recommissioning that space to better suit your needs. I have brave clients who have decided to work from home and have set up their home office in that room. Many times it is right by the front door and is handy for clients or coworkers to reach without walking through the whole house.
I have one client who set that room up as a game room with a table for games. She found that she often had people over to play table games, and found this space offered space for a couple of tables (when necessary) and access to the kitchen for snacks and drinks. She decorated the space tastefully with family photos and a lovely wooden game table and chairs with additional soft chairs for people to visit and play other games. The room is used often and meets the exact needs of the family. Just to be clear, this lady was not short of space in her large home, but the designated "game room" was used by her teenage children and was located upstairs. Using her dining room allowed her to have a more adult space, without taking visitors all through the house.
So if you are thinking about "adding on a room", and you rarely use your dining room, consider using it for something else. The possibilities are limitless. Don't be afraid to be unconventional and do the unexpected. Be a little outrageous!