WorkflowInstances, like WorkflowTasks, are just a specialized data-flow execution sequence. In many cases, you want a set of global (pre-)conditions to all be true in order to execute an entire sequence of WorkflowTasks. In this case, it would make a lot of sense to have WorkflowInstance-level conditions.
|Status||Open [ 1 ]||In Progress [ 3 ]|
|Status||In Progress [ 3 ]||Resolved [ 5 ]|
|Resolution||Fixed [ 1 ]|