Overpowered skills deliberately added isn't something I'd like to see.
I on the contrary would welcome it,but I agree with you that it is higly unlikely.
Come to think of it,it would be a daring step to do that,very unusual and almost revolutionary if that would'nt be a too dramatic way to put it.
Also there would still be some balancing required,for example an "armageddon" spell that kills everything on the screen would't give anyone enjoyment.
I remember once playing quake on god mode long ago:pretty boring quikly.
So I do not think that the overpowered skills were intentional in Divine Divinity,my guess is they were human mistakes.
But I am very gratefull that they did't get nerved in a patch:-)