I'm not much of a blog person but for me I find learning from a blog annoying for the most part. I don't want to watch you build a robot I want to learn from what you learned. The forum works because its an interaction system where you can have input but I kinda think a ton of Blogs for each robot build would be a nightmare. It would also cause less people to write tutorials. I would rather read an article or tutorial on a topic then follow a frantically written blog with missing information and a ton of corrected mistakes.
I feel the same way when it comes to work logs. What you made is always more important than how you made it, except for the few "transistors made by hand" types of projects.
On the other hand I feel like looking at the end product is better than reading a half made tutorial any day of the week, even if only for inspiration.