In terms of design It's a simple conncept of a slider and "custom" and "pre-defined" being on opposites sides. The more you slide toward "pre-defined" the more space devs have to create a compelling protagonist to watch and listen to, but the further they go this way the less customisation is left to the player. The closer you go to "custom" though, the more you ask players to bring with themselves to the game. DA:I was actually pretty hard on "pre-defined" side, except it didn't do much with it. I don't think it counts as being "customisable".
I like something in between best! I love having character creation options, such as picking gender, appearance, and for fantasy rpgs being able to play an elf! These are missing from the Witcher. I also like my character to be memorable and to have some personality, which was missing from DA:I.
