Direct spells are weak. Indirect are not as bad.
Consider manabolt, as mentioned above, compared to lightning bolt. MB does 0 base damage. LB does (Magic/2) base damage. In both cases the spell casting roll is the same, and the resistance roll is similar. But for a Magic 6 caster, LB is doing 3 more boxes of damage.
Now for soak. MB doesn’t have this, LB does. But if your target has lower than Body 6, you’re still going to come out ahead on that roll, on average.
Lightning bolt has one extra point of drain to consider, but again: you’d need to amp up manabolt 3x (at 6 boxes more drain) to equalise it to LB’s base damage. So I think LB still comes out a long way ahead, most of the time. Especially as it also gives your target the Zapped status, to boot.