Usually +spell power items have much less intellect / stamina / spirit etc
Because the gain in damage done for sub level 60 items is so much lower than the benefit the higher stats give you they are often bad choices for gear
I’m using a level 53 stave that is essentially a stat stick +17 intellect & stamina
That’s worth far more than the 30 or so extra spell power with around +7 intellect and stamina I would get from the available daggers and off-hands at that level - I’m still using it at 57