As far as I have heard, dual booting (Ubuntu and Windows) in UEFI isn't very clean
I need to reinstall it to get it in CSM.
This is not true.
As @RodSmith already said, there are firmware bugs or seemingly deliberate faulty implementations. The device manufacturers are to blame for this, not Microsoft! (If you're blaming Microsoft and do nothing against the bad firmware from device manufacturers things will remain as they currently are.)
In case of these issues I was always able to boot from the UEFI loader for removable media.
Also you don't have to reinstall an operating system just for changing the way it boots. You can setup a BIOS Boot Partition on an existing Windows 8 installation or you install GRUB to a GRUB BIOS Boot Partition to enable legacy booting. I wrote what can be done from a perspective of legacy booting (MBR) and Windows 8 (GPT):
The topic is actually trivial from a consumer perspective. As it should be.
Where does the confusion come from?
It's the golden hammer.
While I understand that people would want a tool like
boot-repair, I also want them to read the collection of shell scripts it consists of and tell me that this is well written and documented code (which coding style?) before demanding inclusion in Ubuntu and on the live media, where maintainers would have to maintain the code and possibly improve the existing resolution strategies it uses.
Of course, I know who the author is and it's nothing personal.