I couldn't tell by the article whether or not the stadium was occupied at the time. The stadium may have provided a target that would help to lower support for the war without actually killing people. Obviously any move designed to crush morale isn't going to be "nice", but at least it's better than choosing targets for maximum loss of life.
First of all, this is not remotely technology-related, and does not belong on HN.
Second, according to the IDF, this soccer field has been used to fire long-range rockets towards Israel, and served as a weapons cache.