There are many different opinions about what makes a good blog. Many think that you should include information about yourself. Darren Rowse at ProBlogger has some very good arguments for making yourself available. Not all of us are as outgoing though.
Blogs are the words of people. Some want to be heard and want to be credited for their statements. Others prefer to prompt a discussion, but not be the centre of attention. And some never make a statement at all. At least the first two examples can end up on blogs.
I think there is room for both out there, and the latter should be encouraged. It is just as important to stimulate the discussion as it is to lead it.