"Does the fact that the back-side field is interacting with the iron rotor somehow shape the field through the coil (on the otherside) in a beneficial way? If so then how is this done?"
Yes kind of. The magnetic flux flows through the wire coils, that makes the currant flow, but the steel or iron backing behing the magnets flows the flux to the other poles beside it so it makes a loop. Kinda of completing a circuit. Think this way, flux flows from magnet north pole through wire coil to a mag south pole, then through steel/iron to a another pole, back through another coil and to a pole, through steel/iron to the first pole. Can't really think how to say the path really right now, try this hope close!!
N, coil, S, N pole to iron to next S pole, N to coil to S, n pole to iron to south pole. Makes a complete loop.
South pole would be in first steel rotor, N facing coil, back rotor S facing coil and N facing steel rotor, this pulls the flux throught he coil. The you have two oposite mags side by side so the flux flows from N to S poles through the steel rotor, then back through the coil and back to the original magnet poles. A complete path!