I think the main problem with this, is with visiting your friends Home. Right now, you're able to show the games they have (that you don't), because Oculus just pulls the assets again from the Store. If they're not in the Store, that will be tougher to accomplish.
As a compromise, I'm fine with having the 3rd party cartridges fallback to generic assets for visitors, and just have the name 'typed' neatly onto it. I'm sure most people would be fine with this approach.
ABSOLUTELY! One of my favorite features is seeing my games as boxes and carts lying on a table waiting to be played... it really triggers that nostalgia for me, and I would love to have ALL of my VR games in one place. I can understand if boxes aren't possible because the assets are from a different marketplace, but a cartridge with a simple label should be doable.