A get should never be used as leverage. Period.
If you need leverage for custody, finances, etc, use the beis din and/or the civil system. There are plenty of options for settling the dispute no matter how nasty it gets.
A halachic divorce is not negotiable, however. I understand that many times the wife is at fault and the husband may feel that he is correct in using a get as leverage but I just don't see it because too many times it is abused by the husband.
The Torah allows for a coerced get so I take that to mean that a husband should never be holding it back.
Absolute power, however righteous, is unacceptable.