MySQL's Workbench licensing decision really isn't much of a question of proprietary versus open source. It's about speed of development.

MySQL Workbench has separate windows that allow you to set up user IDs, assign privileges and even view event logs that track database activity.

Although the free cost of MySQL Workbench is very attractive, performance is less than stellar when strained. Many users have also reported MySQL Workbench hangs or fails to respond.