This is a touchy point for many but there are a lot of valid reasons why we disallow HTML on WORLDS or across the site. Here are four of them:
First it's important to remember that WORLDS is more a publishing platform than a diary platform. If you're creating a personal homepage for yourself, then it makes sense to be able to embed HTML widgets and to infinitely customize your page. However, WORLDS is less about personal self expression and more about connecting with an audience, giving people an ultra-clean way to read your writings. The fact that WORLDS have a consistent look to them without the presence of widgets makes navigating a pleasant and seamless process, which should ultimately give you more readers.
In addition to the above reason, Version Vibrant uses much more advanced HTML/CSS than most non-developers are used to handling, so even if we did allow HTML (instead of BB code), members would have to relearn a lot of the basics. For example, by instinct most people would use the < i > tag in order to italicize a word or the < li > tag in order to create a list, but neither would work in Version Vibrant.
Third, there's no way we'd be able to syndicate (or "publish") WORLD posts on theOtaku if we allowed HTML. We'd have to shut down our innovative Fan Words site because it would pose a security risk.
Fourth, allowing HTML leads to support nightmares. With myOtaku we'd constantly get emails from members who, because they forgot to close an HTML tag or used improper markup, destroyed their entire page. Fixing these issues was a huge distraction for us.
We hope you understand our stance on HTML. That said we are always exploring ways to allow non-HTML customization options for you.