While I have generally approached this in an analytical fashion (e.g. this has happened, the data can no longer be stopped, and here are the inevitable outcomes), your outrage is a bit over the top, and I would say over-reaching for a moral high ground. Further you seem to engage in the same sort of extrapolation that has someone declaring being shushed in a movie theater to a slippery slope violation of their first amendment rights.
Comparing the hacking of a infidelity hook up site with government mass monitoring is dubious.
Ashley Madison is not a dating site. It was always, from day one, a site specifically and only for infidelity (earning it millions worth of free advertising via notoriety). The entire rise of that web property came on the backs of the notion that the site wasn't for open marriages or more casual/relaxed notions about sex -- activities that many people engage in with little risk or concern -- but for people who wanted higher risk engagements, whether outside of their own relationship promises, or with parties acting outside of their own relationship promises.
because you suspect most of them might be "guilty" of the crime of "marital infidelity"
Scare quotes aside, moral compasses are personal and vary between us. And the reality is that there are millions of relationships where there is infidelity, often with both parties knowing about it, but more often with one or more party in the dark. It's a risky venture and any of countless things can out one's activities, which in this case is a data dump, making people a victim, truly, of their own actions. It's not hard to imagine why many people may have "glee" about this, as it's somewhat more difficult to find the innocent parties in the churn.
Though I will note that you are being very consistent (I would say to an overly rigorous extent). To address some of the other comments, the parent poster is one of the few people on here who actually very strongly disapproves of what Snowden did (if I recall correctly), so there is no inconsistency. The NSA was a victim, the argument went, of Mr. Snowden's crime.