Very interesting proposition. I DO in fact feels most of the blogging system out there is too much of an overkill for a personal blog for a person that actually have a life (instead of writing blogs all day).
Personally, my wish would be for a blog system to easily create articles (non-blog entries) and display them with different ordering options, as well as the ability to easily add other non-blog content while maintaining minimal overhead.
I did take some look around, the ones that don't have feature bloats are single person projects n the such that has horrible coding/structure and no spam protection and no polish. The ones that actually have good teams behind them are beta software that is rapidly working towards another feature-bloated blogging script.
Of course, at the present Zenphoto itself is lagging behind in the R&D, so if a blog system was to be developed, it'll have to be done by a different team.
...just gimme Zenphoto 1.0.9!