Why do husbands thank and praise their wives for a good well thought out meal?
Why do husbands continue to appreciate their wives when they are not on their best behavior? Only continued appreciation ensures possibility of a change.
Why do wives praise husbands for doing a good job supporting the family?
Why do they continue to appreciate husbands when they do right things but lose a job? Appreciation provides emotional support required for searching for a new job.
The answer? Relationship. Christians praise God because no relationship thrives if there does not exist any appreciation or praise in context of the relationship.
This most relevant reason for praising God is lost to many Christians and may not have been emphasized in your prior circles of Christianity.