This is of course just a temporary issue. We're developing a brand new mechanism to login into blogs which will enable cross-blog authentication. It will be even more useful for your readers than before because when someone will log in once, he will be logged in to every blog on the Engrave platform. This is just because we totally changed the technical way to render blogs.
Logging directly on blogs is one of our most valuable features and it won't be abandoned, don't worry ;)