From the quotes there, the American bishops anticipate that music selection is done by a committee which has received clear delegation from the pastor.
But most musical directors (at least the ones who post on internet forums) dislike that: they would rather be a committee of one, they would never dream of letting ignoramuses choose music, believe no one else has the knowledge and skills etc.
Thankfully a few of the commentators there are more reflective. The best is this one:
All too often, the question of “Who picks the music?” is answered in terms of power. More properly, it should be answered in terms of gifts. Who knows the repertoire and skills of the musical leaders? Who knows the singing abilities of the community? Who knows the resources at hand? Who knows how to blend worship into a seamless event (rather than a stop-start mishmash)?
It seems to me that
- even if you are a professional musical director, vastly more qualified in both liturgy and music than your pastor, choir, musicians and liturgy committee, and
- even if you have all musical decision making authority delegated to you from the pastor
the best way to use this authority is the same way a wise parish-priest uses his authority. Sparingly and with lots of consultation. Ideally in way that your people don't even know that you're exercising authority.
On a very personal level, for reasons of self-protection: The best way to encourage a pastor to change his mind about your role and his delegated authority is a stream of people complaining to him about the music. If people cannot give you input, and see that it is taken notice of sometimes, then you can guarantee they will make their feelings known. If that happens, then best case, the pastor will not let you make the choices any more. Worst case, he'll fire you. Meaningfully listening to other people and developing respectful relationships with them is your best protection against this.
On a more theological level wise stewardship of a community's musical resoures requires making the best use of all the gifts available to you. That means need to engaging people and make them enthusiastic about working with you. That won't happen if you're autocratic. What's more you have both human and theologcial weaknesses and blind-spots, no matter how talented and well educated you are. There will be times when you simply run out of inspiration, when you miss the implications of a scripture message - or when a crisis in your life means that you have to step back and focus on your own family priorities for a few days. Biology means you can only see things from the perspective for your own gender and ethnic group. This means that you need a team to ensure that "the show goes on" and that the message fully reflects the Gospel.
Educationally developing the spiritual lives, liturgical knowledge, musical skill and leadership gifts of the people in your choirs, ensembles and music teams may or may not be part of your formal job description. But I've never yet seen a parish where it wasn't expected, at least informally. If you let other people take part in your decision-making processes, then you will be present when teachable moments, times when you can share liturgical-music knowledge and skill will happen naturally, - people won't even realise that they are learning. But if you work alone, they won't happen - and you won't be there when they happen in the liturgy group meeting or school staffroom.
This goes way beyond the musical skill development that you can share in choir practise - it's about sharing liturgical and practical wisdom based on both Church teaching and your own experience.
And your voice will be most effective if you are seen as a warm and friendly as well as wise and liturgio-musical: A music director's primary role is relational, not melodic.