I've always honestly thought that blogging should be thought of as a tool of thinking and exploration. It helps you refine your ideas by forcing to make vague things more precise. This improves your thinking, identifies gaps in your knowledge, invites the input of others. To me blogging is absolutely invaluable.

I'm biased though because I was a blogger from the start. Maybe the cost of blogging for me is negligible, while it might be more significant to you. My suggestion is to not to overthink it. Use the blog as a tool to outsource your thinking. Instead of guessing what people will like, write anything and see what happens. Then learn from that.

Just my $0.02.