And just to tack on from my prior argument (regarding pre-existing 'out of home' privacy):
Adopting privacy in general is a good thing. Think of the costs losing private information entails:
1) Identity fraud (which makes law enforcement difficult, costs banks money)
2) Scammers (which means the individual loses their cash)
3) Harassment/stalking (once a harasser, stalker, pervert, pedo etc knows where you live, you either have to move - costing a lot of money, job disruption, etc - or ultimately they are going to get you)
4) Datamining for manipulation (Obama campaign, Cambridge Analytica, every facebook experiment ever), which is a major tool for dictators and dictatorships
5) Frame up for crimes (this is a lesser known aspect: corrupt law enforcement will use the details they can obtain in order to 'build a picture' or 'spin a story' sufficient to frame someone for a crime. Alternatively, obtaining leaked information allows them to justify further, minute surveillance, looking for the slightest technicalities from a major historical perspective. CCTV images of you littering? Expect a suspended jail sentence)
6) Strategic Lawsuit Against Public Participation harassment. Critics primary defence against frivilous SLAPP is to write pseudo-anonymously (or wholly anonymously). If data about them leaks, they may face frivilious lawsuits they cannot afford to defend against.
7) Whistleblowers getting jailed. One of the key aspects to whistleblowing in the media (or indeed, in a corporate environment) is true anonymity. Without it, whistleblowers often find themselves charged with technical legalities (such as so-called 'treason' or 'espionage' - despite not working with a 'foreign power') and thus face jail. Journalists, without privacy, cannot provide their sources from scrunity, which lowers the quality of journalism overall.
8) Journalists getting killed. One key issue is journalists who do true mudraking and successfully exposes on corruption, can risk being murdered in retaliation (either by the organisations they expose or indirectly in their line of work, for example, front-line coverage in a war). Without a way to work undercover, protecting their identity (in order to expose corruption), journalists will be forced to 'toe the line' on government affairs.
I'm pretty sure you can expand the justifications for privacy beyond this, but it isn't merely Johnny keeping his weird fetish porn collection safe - this is about life or death, jail or freedom, truth or dishonesty.
Knowing you're truly anonymous, and able to speak out, emboldens free speech.