YOu could switch between doomstones too and you dont have to.
You can stay with one of them the whole game if you want. And you have to find them first.
I really dont see the problem with this one, I think it is great news that this little piece of character customisation is not cut from the game, like so many lovely little features are.
Yea its great something -like- birthsigns are in. But it's like redesigning your characters face midgame, no fun. Stuff like this should define your character, not just be something you can always change / access