I am sure that some have already stated this,
Withholding a Get is Evil, however so is killing someone, but everyone understands that there is a time that we have to use an evil act, such as to kill someone.
I think the same can be said in a Get, although it is an evil act, if however the wife is being unreasonably evil, and the husband is losing everything in his life, such as rights over his own children, I think there is a place for withholding the get.
Why should the husband be a victim to the wife?
Now of course, who will decide if this is the case or not, that is an issue.