I think that a nice to have feature would be to have ALL the properties of a part displayed at one time - one place. Currently if you have custom properties set for a part, you need to open the part to be able to view the settings, or make any changes to them. Alternatively you can also right click a part in an assembly and select 'Properties' but this doesn't reveal very much information.
What I am suggesting is that when you right click a part in an assembly and select "Properties' that you should be able to see, and edit any and all the properties related to that part. this could allow you to set or revise anything related to the part, including all the features listed in the custom properties tab, which is at the part level only.
SolidworksAssemblies