Why did the Ubuntu team not add UEFI capabilities to the Minimal iso?
The Ubuntu help only stated it lacks them:
Note: While the minimal iso image is handy, it isn't useful for installing on UEFI-based systems that you want to run in UEFI mode. The mini iso lacks the proper files for booting the computer in UEFI mode. Thus, the computer will boot in BIOS compatibility mode, and the installation will be in BIOS mode.
And a bug report got triaged with a ....
This issue can be fixed by copying the whole 'EFI' folder of http://cdimage.ubuntu.com/daily-live/current/wily-desktop-amd64.iso into the USB storage made by http://archive.ubuntu.com/ubuntu/dists/wily/main/installer-amd64/current/images/netboot/mini.iso.
Or use this how to.
... but there is no actual source stating why it lacks (U)EFI. I have not seen anyone claim it is due to a copyright issue (that was my 1st assumption). At the moment I would state: because nobody cared about adding it.
I agree that I would like to see this added as well, but the answer is clear, they just haven't gotten around to this yet. Both workarounds in this case can get you where you are going. I used the server install iso myself and forced it into expert install mode by modifying the grub boot entry. This effectively gave me what I was looking for at that time. An EFI mini iso will be great to see when its ready. I suppose I could have made one for myself, but I was using a Windows box that day and I decided to take the easy route.
Just to confirm, it's 5/17/2017, EFI is still not fully supported with the mini.iso.