I work for in local government developing systems containing sensitive information. Some users have rights to edit records, some do not. Numerous and varying factors can effect the rights that even privileged users have to make changes to particular data. Forms are therefore not displayed in Edit mode by default. All fields are disabled unless the user has the right to amend data on the form. In which case they click on the edit button. If they don’t have the right to amend the data the edit button is disabled. We are aware that the system could function perfectly well without using an edit button, however…...
Displaying data in edit mode by default (to those with rights to amend it) would increase the chances of user error.
Further, forcing a click on an edit button ensures that users can not place the blame for their mistakes on the functionality of the system.
Accuracy and validity of information are the most important aspects of the systems we produce. The fact that this method involves an extra mouse click is not of relevance because speed of data entry is not a prime consideration.
In the case of our systems an edit button is an important system requirement. I personally don’t care if that contradicts Microsoft’s Windows GUI standards. I work for Cornwall County Council not Bill Gates.:)