In the American church, it's common to hear of "worship wars", interchurch or multi-church arguments about what and how to sing to God in corporate worship. This leads to one of the great arguments for exclusive psalmody: the unity of the church. The church is unified in Christ and part of her mission is to manifest that unity more and more. This includes our worship; so, what will we sing? The psalter is the only truly ecumenical hymnbook, the only book of songs all Christians can agree to sing. Thus, in regards to the worship wars, exclusive psalm-singers are the peace hippies, sitting cross-legged in their bongo-less psalm circles, calling to the church, "Make worship, not war."
And then, lo and behold, this comment appeared on Ref21's blog from Dr. Phil Ryken in regards to his recent Korea visit:
The hymn-singing was vibrant. I discovered that Korean Christians
typically have their hymnals bound with their Bibles, and that all of the
evangelical churches use the same hymnal (also the same Bible
translation). The advantages of this are immense. Having a hymnal
always ready to hand facilitates greater familiarity with the worship music of
the church. Also, having a Bible/hymnal that cuts across denominational
lines enables Korean Christians to have shared experiences of worship and a
common memory of biblical texts. I couldn't help but be a little
Imagine that! A hymnbook in the Bible - what will they think of next?? And a hymnbook that cuts across denominational lines - why didn't God think of this??
Infectious sarcasm aside, if you love the church (the whole thing and not only your slice of it), sing the psalms! Anything other hymnal you pick up, any other song you put on the overhead is a wedge dividing the people of God.