Why Custom OpenID Login Screens are Needed
Not all OpenID endpoints are necessarily trustworthy. Therefore, administrators may wish to give preferential treatment to specific OpenID providers by designing a customized login experience optimized for a specific OpenID endpoint. In addition they may also disable generic OpenID logins, and selectively enable support for only a specific set of OpenID providers. In this way they can bring greater security to their system.
OpenID is still relatively new, and not every user on the internet understands yet what an OpenID is. For example, both Vox and LiveJournal, two different products, support OpenID. However, many users do not know what their OpenID URL is on these services, much less that they have one at all.
As a consequence they are either unable to or unaware that they can authenticate via those services to leave a comment on virtually any Movable Type blog.
To assist these users Movable Type has provided a specially designed login form for each service to collect the specific information needed in order to formulate an OpenID for each service.