Law schools vary more in character and style than they do in quality. Notice that many closely ranked schools have very similar total scores, and even schools with quite different rankings can have similar total scores. With an insignificant change in the data, such as two additional students passing the bar exam, a school could jump over competitors with similar total scores. In other words, rankings are dangerous because they mask the fact that the differences between schools are negligible on many criteria. For schools that have close scores, whether the school colors look good on you is as important as the difference in rank.
Rankings wrongly make some schools look bad.
Imagine a ranking of all NBA basketball players, and imagine that list being viewed by a person who had never seen an NBA game. If such a person were to read the ranking of NBA players, he might think that the dozen players at the bottom of the list were terrible at playing basketball. Little would he know that they can all play very well. Readers of school rankings might be similarly misled. Those choosing a school might be wrongly influenced to pursue some other career.