Well USB 2.0 is not in OSE, but USB 1.1 works. So you can print directly which is the most usefull case when you want to use vendor provided tools for cd printing or so. The addon feature is basically great to give OSE users the full functionally of the PUEL versions before. I would usually prefer to use the official repository but that way the OSE is not as crippled as before. I am a bit sad about the EFI support. It's seems it is only tested with OSX, that's absolutely great... I would like to have got sandbox for EFI testing because with >2TB hds you have to boot from EFI without an extra boot hd. Let's see what happens before, getting a board with proper EFI support or VBox with full UEFI.
Fortunately Virtualbox has at least one perfectly competent fully open-source replacement whose development has been charging full speed ahead for longer than Virtualbox has been around.
Bochs? Since Virtualbox release it has lost a great deal of attention, as VirtualBox is a fork of Bochs. I wonder if all the great things and improvement Virtualbox have received over Bochs have been merged back? It could be a great time to merge back if not. I'd also love to have the Virtualbox GUI with Bochs.
As far as I know, none of these things were ever a part of virtualbox-ose.
In addition, the target market for VirtualBox is server virtualization and Oracle does not have any interest in doing business with home users, but does benefit from having them be testers. It would not make much sense for Oracle to begin charging home users for closed source components that they currently give away for free, so as you said, I do not see what the problem here is.
Most typical home users would be Linux users wanting to host Windows inside a VM to run basic Windows apps without needing Wine or even for testing Linux distros
Some developers might want the full package for doing server testing/development at home