As for why some users may wish to hide their Age and/or Gender:
Members of Similar Worlds are not forced to use their actual details, although it is preferable.
I believe that more often, honest users feel compelled to provide their actual age and gender, while the dishonest ones may use false information to mislead others.
I believe this new feature will benefit more greatly the rule-abiding and honest members.
For example: Some male users on this site may flirt with every young female they are able to contact privately, whether or not the user has placed a photo of themselves publicly.
This feature can help to reduce unwanted harassment in such cases, limiting themselves from being a target of such behavior.
