Some of the hymns I'm talking about are "Sweet Hour of Prayer", "The Old Rugged Cross", "In The Garden", "What A Friend We Have In Jesus", "The Church In The Wildwood", "Trust and Obey", and "Pass Me Not, O Gentle Savior".
I've put these and others in flat keys for our group, and usually down a step or three to make them easier for people to sing. Every time we do them, a few people come up afterwards and fervently thank us for performing them and telling us they never hear them any more and that they mean a great deal to them.
As a therapist these hymns strike me somewhat as the service tunes and patriotic songs the community band plays on Memorial and Veterans Day. Through a lifetime of association, hearing them triggers an emotional reaction in some audience members that can never be matched by something they've not heard before.
I can understand how church musicians and ministers want to always be exploring new material, but as a therapist these old hymns are a wonderful way to create therapeutic moments for people that grew up with them.