Following Moore's law, with technology advancement, density and speed of integrated circuits have increased exponentially.
[1][2] For counters, Gray encoding gives minimum switching activity, and thus is suitable for low-power designs.
Binary coding is worst for low power since the maximum Hamming distance is equal to the number of state variables.
Thus the combinational part of FSM has lower input transition probability and is more like to give low power dissipation when synthesized.
[6] This technique utilizes dynamic loop information extracted from FSM profiling data for state assignment in order to reduce switching activity.