If you look at the video that was posted earlier with the red dress, you can easily see how much space that enrosque requires.I've been hit in crowded milonga's before by careless leaders when they opened up the embrace to do something fancy like that.
Even if the man has great balance on one leg, it doesn't guarantee that the woman he is dancing with does. She can pull him off balance easily if he is pivoting on one leg.
You may also find that others don't agree that having both feet down allows for quicker changes and compensating to avoid crashes. One could also make a case for the idea that having one foot already lifted means you are that much closer to placing it wherever you want. That is usually the case for followers, and one of the whole points of coming through the "collected" or neutral position.
I think this is going to have to be one of those "agree to disagree" things. Several other leaders have chimed in that they can do the pivot in a tight space and/or are just as stable doing it as when they have both feet down. These things may not be true for you personally, but that doesn't preclude them from ever being true.