The features not included in free are not typically things you can't do without for personal projects (ie, password protection, role based access control, role management for team members, etc...)
Password protection is a pretty basic need and need not cost $45/month. Of course the role/team based stuff for $45/month makes perfect sense because those are only applicable on larger projects.
I've never found a need for password protection on any of the small personal projects I've worked on. But I guess I could imagine some use cases where that would be nice to have.