She uses the title for many reasons but the most prominent is as a display of her power and obvious rank. The Lady King acquired her title through a horrendous event which had the scant few heirs of the past king slitting each other's throats and burying knifes in each others backs. When she was the heir to come out on top she was well aware that the kingdom could I'll afford another such event within its history and decided to take up both crowns at once. She has taken no husband (or wife) and wants her people to know that the kingdom still has a king. Traditionally a male king rules the land with a queen by his side but she is both and she has proven capable time and again.