So turn off the check box that shows you porn games....

You can disable showing adult games from the store in the store preferences.

https://store.steampowered.com/account/preferences

This setting is apparently disabled by default, so at some point you enabled it.

One of the biggest problems is "what is porn?". Time and again a clear definition eludes us and it comes down to personal perception. What one group of people think is porn is not to a different group. Also something to think and reflect about, why are you okay with a store selling intense and graphic violence, but not sex?

Then we get to the fact that it isn't Steam calling the shots on this, not really. It is payment processors. The real outrage here is that Steam is not getting to decide what they do and don't sell, and it isn't a legal problem either. It is an arbitrary choice by the middle man monopoly. And there is nothing stopping their rules removing your ability to buy GTA or Dishonored next.

I think the backlash would be a lot less if this was truly a Steam decision. There would be people upset still, but I don't think to the same degree. The massive outrage is that stores all over, including as big as Steam, are being blackmailed into making these changes.