Fr Seán Coyle, a Dubliner from the Missionary Society of St Columban, works in the Philippines and has added his own comments on the letter in a post on his blog Bangor to Bobbio. Many thanks to him for drawing my attention to Archbishop Villegas' letter.
The Archbishop was at the heart of the ESDA non-violent revolution which toppled Marcos, has fought for democracy and justice all his life, is known as a friend of the poor, and a stout opponent of government corruption. So tread carefully before you set up an opposition between his concern for the cleanliness of altar linens and social justice.
I encourage you to read the whole letter but here is one quotation:
Although we have many duties and functions as priests, in the mind of the ordinary Catholic faithful, we are priests because we can preside at the Eucharist and absolve sins in the confessional. We are priests called to bring to the Lord the sacrifice of thanksgiving from His worshipping people. We are priests called to bring the blessings of God to His chosen people. We are caretakers of the mysteries of God.(The last sentence is from 1 Corinthians 4.1.)