As to the original question, I think the reason for caring what the Patristics say is multi-faceted.
Ex. 1
They had access to manuscripts that today's scholars would [almost
] kill to have.
Ex. 2
Being as some of them wrote within a generation of people who might have met apostles as children or whose grandad was healed by Jesus, the miraculous events of the Bible were quite personal and realistic to them.
Thomas a Kempis well said that Christians should read books on Christ by well-known and respectable Christians and with the same respect as we have for them read small but devout books by small, unknown Christian authors.
He wasn't concened with 'if' we should read other Christians' works, but 'how.'
I tend to agree with that.
There is something to learning what other Chrsitians have to say about this verse or that, in seeing how a certain verse might have effected someone else.
"Iron sharpeneth iron," you know?
Certainly then, there is a value in reading Origen's take on the Canticles, or in brushing up on the early years of the Church as reported by Eusebius.
St. Augustine had a million good thing to say, and so did Ignatius in his letters on the way to his martyrdom.
The Shepherd of Hermas is an excellent piece of early Christian literature too.
It's an equally worthy cause to study the early church fathers as it is to go to church, or to read
Mere Christianity, or
the Imitation of Christ, or anything by Thomas Aquinas.
There is profit in it in being able to see verses from multiple vantage points and in seeing how God works differently through his word for different hearts.
Anyway, maybe I'm confusing all pre-Constantine Christian authors with Patristics.
I'm not sure where the cut off point is, so please forgive me
