Should developers be able to query production databases?

Should developers be given permission to query (SELECT / read only) production databases? The previous place I worked, the development team had the db_datareader role; where I work now the development team can't even connect to the production instance. One of the test instances is a copy of production restored from a production backup once a week, so there aren't any problems with developers actually seeing the data. What good reasons are there for not allowing developers to query production (except for simply not wanting them to have access to read sensitive data)?