is their much point of updating the bios of a mother board apart from bug fixes?
Yes... it's not just bug fixes, some bugs can be a major issue... Google up problems that Asus had with their bios.
so would it be a good idea or not to update the bios of my mobo? gigabyte 78lmt-usb3
I don't know anything about your board. But regardless, my answer would be yes.
When it comes to motherboards
If it's not broke don't fix it.
Depends... some boards have a lot of fixes needed.. notably ASUS.. but ASrock.. you dont generally need to on the x99 .. they are solid all around and they didnt have many bugs