I am a huge fan of this series and can usually put up with casual fanservice beach episodes without making a scene, however this goes beyond the concept of fanservice and straight into the realm of questioning why this even exists in the first place.
Absolutely nothing happened that contributed to the story. I tried to give it the benefit of the doubt and had a sliver of hope that something would remain relevant to the plot of the 3rd season, but even after finishing the 3rd season absolutely nothing carried forward. I laughed a little so I gave it a 3, I suppose.
You will have no regrets skipping this.