For the same reason every diocese is to have a commission on the sacred liturgy under the direction of the bishop, for promoting the liturgical apostolate.
I have to say my diocese has one for music, but not liturgy or sacred art. What about yours?
Sometimes it may be expedient that several dioceses should form between them one single commission which will be able to promote the liturgy by common consultation.
This seems a sound idea, but there are always bishops who are funny about teamwork like this. In my province, Lincoln and St Louis are known for avoiding consultation of most any sort with other dioceses of Iowa, Missouri, Kansas, and Nebraska. Huh. Their loss.