From a web design point of view, the reason that a lot of site admins, myself included, make pictures contingent upon having a login is that it increases web site traffic. The primary reason for most web sites, and I know that you guys already know this so please bear with me, is to generate money. If people can do everything without a login, then they usually do not stay on a site as long, or purchase things as often. Plus, bots and other indexing utilities can then steal pictures off of this page and put them on search engines, without linking them directly here. That also costs a site traffic. Bryan is the boss, so if he wants pictures public then I will gladly do so. Getting a login takes only a moment, and analytical models have shown that it does help business. It's also hard to get a community forum to have new material and threads if you let everyone view and browse everything without a login. I know of some forums that do not even let you see threads without a login. Car forums are commonly set up that way. I hope this helps, and answers your questions

The impossible missions are the only ones which succeed. -JYC