Adding droop in a voltage regulation circuit increases the headroom for load transients.
At high currents, even a small resistance results in substantial voltage drop between the regulator and the load.
In a regulator not employing droop, when the load is suddenly increased very rapidly (i.e. a transient), the output voltage will momentarily sag.
Conversely, when a heavy load is suddenly disconnected, the voltage will show a peak.
The output decoupling capacitors have to "absorb" these transients before the control loop has a chance to compensate.