Dave Hirsch:
‘Yotzah Blo Kesuba’ is only applicable to married offenders. Unmarried offenders also need to be dealt with. Hence the aforementioned ideas.
Additionally, although (as you said) ‘Yotzah Blo Kesuba’ is a valid and necessary punishment for married offenders, it would prove insufficient. This is due to the fact that these brazen offenders would likely resort to non-Jewish courts (in another violation of halacha) to pursue their divorce case and receive monies they are un-entitled to under Torah law and halacha – as properly administered by Beis Din.