Not because of the leaks, but because of their actions. That's an important distinction.
If you take actions like this, you should be prepared for them to be exposed, and if you use the argument the NSA and you yourself have made here (it would be ok if we were evil and no-one knew about it), you should expect no one to trust you. You've just declared yourself untrustworthy and a bad ally in perpetuity, because you think this is ok as long as no-one knew about it.
Right. I agree with that. There's actually sort of a boolean AND. Because we did them AND we got caught.
My guess is that all major players are doing the same stuff and that if the US doesn't participate it loses. I doubt the US hacked Germany on a whim - I bet it was a pretty labored decision with cost-benefit analysis (one being chance of getting caught).