Image via WikipediaI think it's because of an ambiguity in the word "prayer". The obvious and primary sense of prayer is a petition to an object of worship i.e. God, in our case. A secondary sense which is by now an archaism, but which nonetheless exists, is an earnest petition to a person. So we ask them to pray for us or, to put it another way, we pray them to pray for us.
Worship is right out - as I hope you assume already, of me, if not my church. There are two words in Greek, latria and doulia, usually rendered "worship" and "veneration" respectively. Latria is worship that should be due only to God, hence "ido-latry" and "Mario-latry" are very-bad-things. However, doulia may also be rendered "worship", as the root of the word which tends to denote latria is "worth-ship" or worthiness. This is obviously a misleading use of the word, which we now apply only to God in common usage, though not in the courts, where we are expected to address certain magistrates as "your worship". I mention this only to suggest that there are complications of language involved; basically, we don't worship saints.
It's about asking them to help us in the same way we might ask any Christian to help us.
For a dogmatic church, there's a remarkable amount of room for individualism within Catholicism. It's largely a matter of personal devotion. Within corporate worship, we pray to Mary very regularly, as follows:
Hail Mary, full of grace, the Lord is with thee; blessed art thou amongst women, and blessed is the fruit of thy womb, Jesus. Holy Mary, Mother of God, pray for us sinners, now and at the hour of our death.Though this probably gets the old alarm bells ringing theologically, as it once did for me, you can see that it's basically a prayer for her prayer. We pray to the saints and angels en masse, within our general confession as follows:
Amen.
I confess to almighty God,On certain occasions we will have a litany of the saints, where we simply ask a lot of saints one after to pray for us - i.e. "St. Benedict, Pray for us." - and we have All Saints on November 1st. Individual saints are remembered (or not) at masses throughout the year, though in such a way as you might well miss it if you're not paying attention. I think that's about as much as comes from the initiative of the Church really.
and to you,
my brothers and sisters,
that I have sinned through my own fault,
in my thoughts and in my words,
in what I have done,
and in what I have failed to do;
and I ask blessed Mary,
ever virgin,
all the angels and saints,
and you,
my brothers and sisters,
to pray for me to the Lord our God.
As I say, it's about personal devotions really. I don't pray to the saints much, but sometimes I pray to St. Justin Martyr - my name saint, St. Polycarp, St. Augustine, St. Maria Goretti, St. Francis, and a few others. Back in the day, I believe the cultus of saints tended to develop spontaneously, especially with martyrs, but these days the Church recommends certain "righteous men" whose prayers we can therefore expect to be "powerful and effective" (James 5:16). That, in essence, is why we do.
