Narcissistic exercise?

I just watched the video of Mena Trott talking about blogs again and it struck me just how egotistical and narcissistic blogs really are.  They are entirely about the bloggers feelings, experiences and emotions...even when I'm writing this I am thinking, why should other people care about what I am writing?
I imagine that some degree of introspection or narcissism is useful and healthy to some extent as it helps you through complex decisions, but is blogging about your everyday mundane life really necessary???

I remember thinking this when Twitter was first introduced, as the site struck me as extremely self-serving, especially concerning celebrities.  I suppose people are essentially nosy and there will always be something wanting to probe into someone's else's personal life, so in that respect, your blog is never entirely yours in the first place, it is public property.

Jenny