If this was all new information I might disagree with you, but we already knew capital gains is horrendously undertaxed. And knowing the specific dollar amount doesn't change the conversation much, it just makes it that much more incendiary.
This brings the knowledge everyone sort of knew and makes it common knowledge. That can have a powerful impact.
Have you considered the amount of identity theft that can occur when you have 15-20 years of tax information on thousands of individuals? And that information has obviously been duplicated many times if it made its way from the IRS, through an informant, and into the hands of at least one person at ProPublica?
I don't intend to defend "the system" and the fact ultra-rich can become even more ultra-rich, or the morality/fairness of that. I do find it very alarming that its apparently "OK" that Pro-Publica has intimate financial details of thousands of Americans - enough to completely ruin their lives if in the wrong hands - and its "OK because they have a lot of money".
Thats not OK to have on any American, wealthy or not, in my opinion.
Have I been living under a rock? I think we may have suspected that the ultrawealthy was not paying their fair share, but paying nothing? Using elaborate loopholes to actually get out of any tax burden at all? I found that to be shocking.