There are, in my opinion a couple of things that I would imagine contribute to what the Op wrote (assuming that it is the case- I really don’t believe it is)
1.) People will always sympathize with the person who no longer wishes to be married. Forcing someone to remain married to someone who they do not wish to be married too will (justifiably) leave a bad taste in most people’s mouths.
2.) Women tend to be viewed as the underdog in most fights they have with men (although this is not necessarily the case and indeed these days when woman have equal rights they are in many cases on equal footing-this was however not the case even 100 years ago in both frum and secular society)Most people are inclined to support the Underdog.
3.)According to Halacha A man getting his needs taken care of by other unmarried woman if his wife refuses a divorce is at most transgressing a La”av and is at most chayiv malkos mdirobonnon while a woman doing the same exact thing is considered on par with a murderer and would according to Halacha in an ideal world be executed.
Although it sounds nice to say “withholding a get is never justified” bad divorces can be REALLY bad and if a woman is withholding a man’s children or otherwise abusing him I would not judge the man for using whatever leverage he has to get her to stop; up to and including withholding a Get