[MRAB <python@mrabarnett.plus.com>]
I eventually decided against having it added to the standard library because that would tie fixes and additions to Python's release cycle, and there's that adage that Python has "batteries included", but not nuclear reactors. PyPI is a better place for it, for those who need more than what the standard re module provides.
I think it's a puzzle with no good solution. For example, while atomic groups may have been "nuclear reactor" level in 2008, they're ubiquitous now. regexps in industry practice keep evolving, and so does your regex module, but Python's re module is frozen in an ever-receding past. Nobody wants to work on it because, well, "regex already does that! In fact, it's been doing it for 15 years already". Your module is _too_ successful for Python's good ;-)