custom hierarchy icons?

(See attached image)

I just started using SuperTiled2Unity and noticed that they manage to include a custom icon for their imported tilemaps in the hierarchy! It got me thinking... "boy wouldn't it be nice if we could easily set our own custom hierarchy icons?"

This seems like such a small thing that would be a huge quality-of-life improvement! The player would have its own unique icon, enemies would all have enemy icons, cameras would look like cameras... etc. Makes things easier to find and more distinct.

So, two questions:

1) Is there a (relatively) simple way to accomplish this?
2) Why hasn't Unity done more with this up to this point? All we have are cubes for everything in our hierarchies... :/

 

I agree, this would be a really awesome way of being able to identify certain objects.