Browsers are already having a really hard time making users of average proficiency understand SSL feedback and act wisely in response to warnings. Whatever spec

Browsers are already having a really hard time making users of average proficiency understand SSL feedback and act wisely in response to warnings. Whatever special case they add to the UI to accomodate geeks using self-signed certs becomes yet another complexity that the normal user has to understand. Also, consider that there are probably some users who think they understand the implications of trusting a self-signed cert while they actually do not, and the browser has no way of differentiating this.