When the Nazis came to power, they used those previously obtained lists to round up the homosexuals and send them to death camps. A lesson that privacy matters even if you think your current government and/or its use of data is benign.
Beyond that, by saying it's ok for governments to snoop on private communications, it's normalising that same behaviour by China, Russia, Saudi Arabia, etc, etc. It's not good enough to say that it's alright for the West to do it because they are good guys and not ok for despotic regimes to do it because they are bad guys. It's a matter of principle that it's wrong for everyone to do it.
That is the only way to set a standard and hold every government to it. We should figure out what line in terms of privacy and respect for personal rights we would like China, Russia, etc to abide by. It's only ok for our governments to do things that we would accept as being legitimate for those governments to do. That is the only way to normalise respect for the individual and protect our personal freedoms in the long term.