I say go for it! Boys/men always have their stuff all over the place, my husband's "work room" looks like a tornado went through it. So I took over our home office, I stripped the ugly wall paper down that was up there from the previous home owner. I fixed the wall and painted the room (while he was on the road), put up the wall decor that I liked and took over one side of the office for my sewing/work area.
So I think you should have your own private place it always seems when we have families we always give everything to everyone else but we don't always do things just for us. Tell the family that you will be a more relaxed person if you have your own sanctuary.