What is the wisdom behind prohibiting music and singing, even though they have therapeutic and practical benefits?

Singing has different types, and each type has its own ruling. Its prohibition is not waived just because it is less dangerous than other forbidden things, for prohibitions are of varying degrees. Singing is forbidden because it leads to heedlessness, hardness of heart, and arousal of desires, and it may distract from the remembrance of Allah and prayer. It is permissible to use singing as a treatment if this is confirmed by the testimony of two trustworthy doctors. This falls under the category of necessities that permit forbidden things, as Allah Almighty says: "And He has explained in detail to you what He has forbidden you, except what you are compelled to [eat or use]" and His saying: "But whoever is compelled, neither desiring [it] nor transgressing [its limit] - then there is no sin upon him."