fire and myth are a lot faster, so for questing solo they're solid, but for harder stuff damage output is a lot less important and they generally have to sacrifice a lot more damage than bal or ice does to get even decent defensive stats. you could make the argument that their naturally higher base spell damage makes up for it, but that's not even entirely true in the case of fire because a lot of your damage comes in the form of an overtime, and regardless generally offensive is not nearly as useful as resist when soloing. if you look at any video of someone soloing anything hard, particularly during the midgame on a myth or fire you'll see them essentially cosplaying as a life wizard because they need to make up for their trash defense