Let's say Regina wasnt the best one for the job as the Community Manager, she wasnt very personable, she was a bit stoic when when talking to the community, hard to get in touch in Guild Wars 1 and the same with Guild Wars 2, and out of touch with the playerbase, she is distance from everyone else, very different from Gaile. People didn't like it at all and all of the time since then people wanted Gaile back ever since then.
She isn't actually doing anything else. She was always in charge of the social media stuff and was the more hidden member of the community team. She really already had the position in all but name, they are just moving the social media out into it's own little hut.
Now the timing is interesting. It could be that a restructuring of the CR team was planned and a reason that Martin was annoyed. Or it could be that Regina is so much more well versed in the social media aspect than Gaile that it just makes sense to split it now. Then again, the new position is still under community so it could just be a subsection of the team under Gaile instead of a separate entity. Community Marketing would be this weird middle ground between two separate teams so it isn't really obvious how it goes.
I've friend-ed Gaile on her facebook, she hardly post anything on it and ever so often. I think Gaile and Regina are in the best places for the Community at large and the game as a whole. Guile on the Community team and Regina on the social media sphere.