1. Accessibility
HTML5 makes your blog be easy to access, because there are two main reasons. Its are semantic and ARIA.
2. Code Cleaner
The best solution for you if you want a simple code , elegant, easy to read then the answer is using HTML5. By applying HTML5 you can write a descriptive code and semantic code which allows you to separate the meaning of content and style.
3. Storage
One of the advantages of HTML5 is the storage features. This storage includes cookies and database. HTML5 has a better security and performance and the data will remain safe, even after the browser is closed.
4. Best Interaction
All of you sure want a better interaction. You definitely want your website more dynamic and allows users to enjoy and the interact with the content you create.
HTML5 is the technology of the future. The only real reason of the users prefer to use HTML5 is just to write code coexist and fun features. You just started using it and is does not change the way of your design. It's very simple and you have to start to try.