When someone says "We've got horrible things to reveal", your imagination fills in the blanks, extrapolating from what we've already found out to even more horrible extremes.
But then what Wikileaks revealed didn't live up to that. It was pretty much more of the same things we already knew.
It's no wonder the reaction was subdued. It doesn't mean people don't care, it just means we're too burnt out to work up a rage about the sorts of things we already knew were happening.