I would not use an interior decorator, my house is my house and has to adapt to my use of it, have my choice of furniture and my choice of colours.
However, I some times think I would like a stylist to walk round the house and tweak it a bit. When I was selling a relative's house, I did a thorough House Doctor job on it, reducing contents and ornaments, moving things around. The Estate Agent was approving and it helped sell the house and a lot of the feedback was complimentary.
However I am too close to my own house but I am sure that there are small tweaks here and there that if made, would make me feel even more comfortable in my own home. My immediate surroundings bathe my peace of mine.