As has been pointed out, a go-around is a perfectly simple manoeuvre. However, that is not what makes its execution a requirement to file an ASR. It is the reasons that the go-around was carried out that help others in the company or the fleet (or elsewhere).
Hence, I recently filed an ASR when I told my FO to go-around when he allowed the aircraft to float after a hot and high approach in a cross-wind to a downward-sloping runway. We were positioning empty, so I had decided to let him discover the results for himself rather than being told - far better instructional technique at times! Also, if one only ever carries out a go-around in the sim at 6-monthly intervals, the mind tends to relax when flying the line.