If something works for you, that’s great. Now, whether some cool new feature is worth the time and effort of integrating into the WordPress core is another matter altogether. Significant changes are discussed and debated (see the Ideas forum).
Alternate editors have been implemented via plugins (see FckEditor for WordPress as an example. It is possible (and I think has been discussed) to allow the option of choosing from multiple editors may be built into WP, but for now, that’s still mostly an idea.
To replicate the basic functionality of that editor:
(1) Turning off the visual editor
(2) add a markdown intepreter plugin: Markdown for WordPress and bbPress
(3) Hack your install’s Quicktags or use a plugin such as AddQuicktags
I actually just recently implemented WMD into my WP 2.5 blog that I’m currently building. http://c.hadcoleman.com/
I’m probably gonna create a WordPress plugin for it. Stay tuned, if you’re interested.
And here it is: http://c.hadcoleman.com/wordpress-plugins/wmd-editor-wordpress-plugin/
This site is actually still in infant stage, as you can tell by all the dust. But this plugin was so easy to throw together…