At the church that I attend in the morning, we haven't been using the Revised Common Lectionary. In fact, we haven't used in several months. The pastor doesn't care for it as much.
I really didn't know much about the Lectionary until I entered seminary. Most of the churches I attended growing up never used a lectionary, so this was new to me. As someone who loves order, this was kinda cool, so I started using it and as long as I have been preaching, I've used the lectionary.
I've been wondering why one would use it. Of course, there is nothing in choir that states "thou shalt use the lectionary," but as I've thought about it more, I think I've come up with a reason why I use it and why it might be good for churches to use it:
Let me explain. The lectionary is something that is pretty public and shared with everyone, so the average joe can look up the scripture for the coming Sunday and read and study the scripture. In the old way, were the pastor chooses the scripture, the knowledge of what the texts are rests with the pastor. The congregation doesn't always know what is going to preached that Sunday and can't really look at the texts ahead of time. Maybe it's me, but I like that fact- parishoners can look at the upcoming texts along with the pastor.
The other thing is that it tends have the pastor preach texts that they would not ordinarily preach from. When the pastor decides, there is too much temptation to find verses that one likes instead of having to preach some very uncomfortable texts and wonder where the gospel can be found.
Again, the lectionary is not some law handed down from God. However, I think it has it's plusses and this is one of them.