There are several reasons why some people in the medical comminity still use the term, in spite of it's innacuracy:

1. It's what they're told is the term to use and most people (including doctors) are basically myrmidons.

2. It's an old trick to over define a word in the attempt to "normalize" the perception of what it actually means. Thus Pro-Choice becomes anyone who approves of any abortion, not just all abortions as is the current law. Evolution becomes any change, even in an individual orgnaism, rather than the actual change from one species to another.

Some people want more acceptance for true hermaphrodites (a good cause) but are willing to bend the truth in order to sweep other people into the definition so they can then use those people to bolster their cause. Hurting one group to help another  makes their noble cause un-noble by resorting to less than honorable methods.

3. Some people don't like our current definition of gender, and wish to rewrite it. Redefining as many people out of the current definitions makes that jobs, supposedly, easier. Truth and Fact are merely annoyances to get around.