I sometimes use {html} mode to do formatting beyond what I can get with Confluence's markup language.  An example might be:

The formula for water is H{html}<sub>2</sub>{html} and it is 1g/cm{html}<sup>3</sup>{html}

When I later view this page in Rich Text mode, it becomes:

The formula for water is H
{html}<SUB>2</SUB>{html} and it is 1g/cm
{html}<SUP>3</SUP>{html}

Which appears as:

The formula for water is H
2 and it is 1g/cm
3

This happens even if I wasn't editing this section -- anyone who edits such a page in Rich Text mode will destroy the formatting.  I've seen more complicated and disasterous results as well.  In general the Rich Text editor just doesn't seem to understand the {html} tag and has a tendency to trash anything done with it.

I consider being able to use HTML when all else fails to be pretty crucial.  So hopefully this can be fixed.  Thanks!