It's possible to defy the rules and produce something awesome. But often you just need to produce something that's reliable, sturdy, useful and quick. Learn the rules first. Use them most of the time. Break them when you've got a rare, wonderful reason to do so.
Blogging is the most conversational form of writing out there. The best bloggers conjure up structures that are so subtle and sophisticated that everything seems totally free-form. Getting that right consistently is a gift. Switching into conversation mode 100% of the time and hoping for great results is like pressing together some notched pieces of wood and hoping for the best.