Saves electricity, adds moisture to a dry room, isn’t rough on your garments like a dryer, feels quaint and European
Edit: Apparently, doing this too much can cause mold issues, so do it sparingly! And definitely don’t do it on an electric radiator.
I came by it the hard way, but unfortunately it is superior to the dryer for just about all fabrics but towels. Use less energy, make your clothes last longer, plus your house smells like fresh laundry.