Why did Imam al-Shirbini state in "Mughni al-Muhtaj" (4/207) that the Sunnah is to be content with one wife unless there is a need, despite the fact that marrying more than one wife is a Sunnah?

Polygyny is considered better for a man whom one wife does not suffice, or who needs more than one. However, for a man whom one wife suffices, it is better for him to restrict himself to her. Many scholars have held the view that it is preferable to restrict oneself to one wife, out of fear of injustice and family dispersion. Polygyny is not considered a Sunnah that is unconditionally recommended. The noble verse (Fearing that you will not be just, then [marry only] one) indicates permissibility, not recommendation.