A few quotes from 15Dec WT (study"sing to Jehovah")
15 As time passes, refinements are made in our understanding of the Scriptures.
Proverbs 4:18 says: “The path of the righteous ones is like the bright light that is getting
lighter and lighter until the day is firmly established.”
Increased light inevitably leads to adjustments in the way in which we ‘sing the truth.’
For the past 25 years, Jehovah’s Witnesses in many lands have enjoyed using
the songbook entitled Sing Praises to Jehovah. In the years since that book was first
published, the light has been getting brighter on a number of topics, and some of the
expressions used in that songbook have become outdated.
16 For that and other reasons, the Governing Body approved the publication of a
new songbook entitled Sing to Jehovah. The number of songs in our new book has been
reduced to 135. Because there are fewer songs to learn, it should be possible for us to
memorize the lyrics of at least some of the new songs. This is in harmony with Paul’s
counsel recorded at Ephesians 5:19.—Read.
Other reasons?