Consider:

All light magic benefits, except the stat boost from day of the gods, can be gotten via elemental magic.

There are a ton of divine intervention scrolls laying around ( land of the giants ).

With dark magic you get shrapmetal, dragonbreath, armageddon and souldrinker, the best damage spells in the game. Not to mention reanimate, which can lead to some real experience cheese by killing and resurrecting the same monster many times.

The light magic relics suck.

Ethric’s Staff is amazing!

Lich's gain resistance and immunities upon transformation.

Being bad is good.