Why has this configuration chosen for feedback?
You're asking what the role of R1 and C2 is. This circuit is a PI controller. 

With just R1 in the feedback path you have a simple amplifier, with a proportional response. With just C2 in the feedback path you have an integrator.

This circuit combines those behaviours. The faster the signal changes, the more C2 looks like a short and you have a simple proportional feedback through R1. The more slowly the signal is changing, the greater the role C2 plays and the circuit is an integrator.

So, with the proportional response dominating at high frequency, the circuit can rush toward the setpoint faster, then when the output is in the right ballpark the integrator takes over to stabilize it.