This scheme is great for testing. It allows you to log into the application by supplying just a username, as if you logged in normally - saving on user management in test servers.
The login screen used isn't page 101, but a generic page generated via wwv_flow_custom_auth_std.login_page. Prior to APEX 5 the page looked rather ugly.
|APEX 4 Open Door login|
As with many other aspects, the page now looks much tidier in APEX 5.
|APEX 5 Open Door login|
I think this upgrade can also encourage a little sprucing up with some script that can be applied via the authentication screen Help Text, in the same manner as the workspace login can be customised.
|Authentication Scheme settings|
$('h1.a-Wizard-title').text('Open Door Credentials, great for testing')
Actual help content could also be supplied, so the login screen could be adjusted to suit your needs.
|Customised APEX 5 Open Door login|
Amazing what a little jQuery can do.