Hi Ed,
The context is a bit different. A blog post is a published article so we typically want to associate the author's real name with the article.
For forums or comments we cannot assume the user is cool with us revealing their real name as entered in the user profile so we show the display name and it is up to the individual user whether to use their real name also in the display name.
I agree on the internal comment system we should hide the un-needed user inputs for name, email, and website by default if the request is authenticated. I've just fixed that for the next release.
Best,
Joe