You're right. There are many reasons we haven't devoted time to remedying this:
WikiCreole is more or less a dead project (we plan to support one or more alternatives at some point)
The Bitbucket-specific macros are not necessarily rendered correctly in the preview
We have some wonky CSS, so even when the client-side converter generates the correct markup we don't necessarily display it correctly!
Thanks for the info. Those are some challenging constraints.
I'm a bit fan of markdown. Either way I look forward to alternatives even if it means discontinuing support for wiki markup.
I, too, think Markdown's great. We plan to give users the option of using Markdown rather than WikiCreole when creating issues and pull requests, and when adding comments. I'm very keen to get Hashify Editor into Bitbucket. :D