Brad Frost shares a couple of stories about how people have remembered his writing because he has his own blog. He puts it very clearly:
Writing on your own website associates your thoughts and ideas with you as a person. Having a distinct website design helps strengthen that association.
This is why we encourage everyone to have their own blog and use their own domain name, and why Micro.blog-hosted blogs have multiple built-in designs as well as support for completely custom themes. I highlighted a few custom designs in the 12 days of microblogging series, and I recorded a YouTube screencast last month explaining how to import and customize new themes.