What is the Purpose of State Group Icons?

It is helpful to see that state groups have icons associated with them. Work items that are "In Progress" have a little progress bar in the corner of the work item type's icon. This is useful because you can see at-a-glance when viewing a list of work items, which ones are in progress. However, it would be nice to be able to see more state information at-a-glance. For example, we have a state in our workflow called 'Pending Approval'. When a work item is in this state, this is the indication to the reviewers that the work item is ready for them to approve. This is useful because approvals may be added prematurely in some scenarios. It would be great to be able to scan a list of work items and be able to see which work items are in this Pending state. At present, none of our state groups have any icons associated with them. As a test, I added an icon to this 'Pending Approval' state. However, it doesn't appear like this icon is actually used anywhere in the tool. The icon doesn't appear as part of the work item type's icon, in any fields in the editor presentation, in dashboard widgets, etc. So the question is, what does this icon actually do? Is this just stubbed in capability that isn't actually being used for anything?

As a secondary question, I think I may have asked this before, but am not sure. Is there a way to control the icons that are displayed in the corner of the work items based on their state groups? I had hoped that assigning icons to the state groups would have this effect, but it clearly doesn't. Is there some other way?

Edit: It looks like my second question has been asked before here https://jazz.net/forum/questions/125744/are-work-item-decorator-icons-customizable