What do you think of combining the previous and following step? I'm looking at it and it seems a good bit busier than the rest of the installer so I would say no, although I think we should reduce computer-name to only the input box and advanced button as is shown. After reading over the RFCs I think it's safe to say that the reasons underlying those suggestions are probably not applicable to the average Ubuntu user. If you are at a place where hostname matters and you don't feel comfortable clicking the advanced button, you are probably not installing your own OS either.
So err, maybe like this?