Why did the author (Ibsen) choose to have Torvald use so many nicknames when addressing his wife?

Torvald’s attitude about his wife pervades every word he speaks to her, and his objectification of Nora is most evident in his diminutive pet names for her. She is his little “lark” and “squirrel” and, later, his “songbird.” Similarly, Torvald repeatedly calls Nora his “little one” or “little girl,” maintaining the atmosphere of subordination more appropriate to a father than a husband.