AZ,
1. Why wasn’t there a shidduch crisis when polygamy was in effect? It should have resulted in their not being enough wives for all the men, as some men had multiple wives.
Obviously, this is normal and how G-d wants the world to run insofar as shidduchim are concerned. Same in our days.
2. If the shidduch crisis today is not enough husbands, then if we reinstate polygamy the women who today (allegedly) would otherwise never be able to get married, could marry a man who already has another wife.