This is a very modest effect, given that US wages went up by a good amount during the time period in question. I think that pay transparency is a good idea in theory but in practice people's well-being can suffer. This is a good rundown on the psychological and economic pitfalls. The best argument I have read is that no matter what the pay distribution is, 50% of people will be below the median wage, and being in that 50% honestly feel pretty bad. Few of us humans think we are in the bottom half of our field or workplace, yet obviously 50% of us are. There is ample empirical evidence to support this point.

tl;dr This law didn't actually cause a huge jump in wages and also laws like this can make people pretty miserable and we shouldn't pass laws that make people feel sad.