Prayers and song are an important part of the ritual of religion. I'm only slightly surprised that the WTS would remove either, let alone both. But Rutherford was something of a maverick, and I get the impression that he badly wanted to leave his mark on the religion. There doesn't seem to be anything he didn't try during his tenure. Knorr seemed like more of a traditionalist and by-the-book type, who perhaps better understood that routine is very important for people.
Rutherford was probably the biggest grifter in the organization. The whole charade with 'the return of the worthy ones' provided him with a mansion to live in and two luxury cars to drive around be driven around in. He got to loudly wag his finger at governments and religions, and only occasionally had to eat his words (and did so without hesitation- most bullies are also cowards). That a group of people still lionize him as "judge" should be an embarrassment, but here we are.