We would like to display a custom copyright text. At the moment this can only be done by overriding the default behavior in PHP. A more user-friendly and maintainable way would be to provide a theme settings screen where this is editable, as for example Elbee Elgee does.
Having the current year being automatically displayed in the copyright might cause trouble. A fundamental part for obtaining a copyright is the requirement of an original work. When a copyright is contested, the question is whether there was prior art that this work was based on.
Example: Person A posts an article in 2013. Person B copies it without permission to their blog during the same year. Year changes. Person A's blog automatically generates the copyright date and states that the content is copyrighted from 2014 onwards. Person B's blog doesn't automatically update the copyright, and it shows that their identical content is copyrighted from 2013 onwards.
Copyright notices don't have legal effect in themselves, but they can be misleading, which can have ramifications when trying to enforce one's rights. When one is making a copyright claim it's best to be accurate and at least not claim that the copyright is newer than it is.
Better defaults go only so far
A better automatic copyright notice would be from the site's founding year to the current year. Of course, if site content wasn't updated in 2014, there's no basis to claim a copyright being obtained during 2013 to 2014. The only way to let users make accurate statements of their copyrights is by providing a manually editable field.