One of the biggest issues during long development is an evolving product and changing direction. This plays havoc with assets as you can only ever be organised with the current direction of your project. I have found over production the need to rearrange assets is a must. The problem is doing so breaks half your game as everything depends on traditional paths. The path has been used in computers since there inception and I personally believe it is an old concept which needs replacing.
Assets in UnrealEngine are packed into UASSET files, I propose each one of these is giving a unique identifier. These files can be moved anywhere within the content folder and your content browser will be updated accordingly. I think its easy to under estimate how much this feature could benefit production, often when working with larger teams great content can be lost as things gradually become more disorganized. The ability to do spring cleaning is a must! This also plays into the hands of UnrealEngine market place. You could download content and move it a location that suits your project, not just the path which it was created.