I believe This change isnt just for parents to be happy with steem we are also hopeful (though there is no guarantee) that we will be viewed more favorably by system administrators whose job it is to block (or not) websites on their networks for work, schools, libraries and maybe even some countries etc. Unless logged in they should see a lot less issues that would cause us to be blocked.

If they dig deeper they can see they can instead block the image/video repositories, and generally that's what we have thankfully seen is steempeak has not been blocked so we are just thinking ahead.
... in the end we hope we can work with them to resolve any issues and let our users use our site on their network. Their internet source is their property their network and they get to decide but we hope they talk to us first and we can work through it. We are aimed at popular content creators in the long run so often those fans are young and using wifi they didnt pay for that has rules.

But also it's more than parents and system admins... there's just a lot of people who want all 3 of these options and it solves all the scenarios nicely we believe.
Love to know if it solves any issues you have and if you'd now give your kid an account with just the posting key?