I can't tell you how much content I've deleted in the past, opting to write new instead. I've literally re-launched my blog multiple times in order to put something new and better out there. What a mistake that has been as the old content was great for several reasons.
Blogs are more about personal preference and opinion than fact. If it were about die hard rules and processes, a static website would be more in order. The blog is to be fluid and show change in the line of thought of the blogger.
So why is it that I've spent so much time working to perfect my blog when imperfection is critical to successful blogging? I suppose you could say that I missed the point to blogging, maybe it was just part of the learning process. Whatever the reason, I doubt I will be deleting old content anymore.
What if I was able to take my content, putting it in order starting from the beginning and seeing the progression of ideas throughout my growth stages as a blogger and in real life? Just being able to go back and take a look throughout time would have offered so much more insight into where I'm going in the future.
Keeping old content in tact has other value beyond a record of your past, it helps to establish the blog with other sites and search engines. When a deep historical archive of content is present, chances are other site and search engines will see my blog as being more than just a startup but an established blog worth indexing.
So as you can see, I need to let my thoughts and ideas flow freely through my blog so that I can deliver a stronger message, while retaining my old content which shows my progression as a blogger.