UE4 really lacks in some organization tools:
1 - Remove unused textures, shaders, and other elements.
2 - Collect BP: Please give us a tool where it takes everything inside a BP and collects them in one chosen folder in the same project, everything used in the BP gets moved to that folder from shaders to textures to animation and objects.
I’m sure there are more areas to cover but these two can drastically improve everyday tasks.
Editor scripting with Python serves this purpose.
Look at script examples: GitHub - mamoniem/UnrealEditorPythonScripts: Some of my personal scripts i made to use for my own projects, but free of charge to be used for any project and any purpose as long as it is not violating the LICENSE file or the Unreal Engine EULA.
It would be extreme mess to put a big percentage of assets into “blueprint assets” folder. Everything can be used in blueprints and it’s up to team to work on clean folder structure.
Of course, if you want this badly, try python scripting: iterate through all blueprints, get all assets in reference chain and move it. It’s very specific need and writing your own scripts is the best way to fulfill that need 
Python scripting is a bit out of our reach at the moment but thanks, to explain further on the second point. Sometimes while working we try out different textures and objects in a BP in a separate temp project file to make sure things are working. Things move fast and we end up not using a lot of assets in different folders and no time to be organized while trying things out. So when you want to get organized and finalize the BP asset, I end up looking one by one for textures used and objects neglected gathering them manually in one folder and then migrating them to the core project content file to arrange them in respective folders there. That looking for assets part takes a bit of time sometimes, this is why in applications like 3ds max and many composting software, we have options to “collect files” in one folder so we know which assets are used to be re-arranged or exported later.
Will check it out, I think if this tool works as advertised epic should just buy it off and implement it in UE for the sake of all of us.