I actually attended a shiur a number of years ago on the topic of Cherem D’Rabbenu Gershom (I wish I could remember who gave it).
Rabbenu Gershom was not responding to sensibilities. There were practical halachic issues. Way back when, many Jews were merchants (hard to do much else because the authorities kept restricting Jewish employment). Each Cherem instituted by Rabbeinu Gershom addressed issues regarding these merchants:
1. Not opening another person’s mail was meant to keep other merchants from finding out about competitor’s deals, inventory, suppliers, etc., so as not to sabotage someone else’s business.
2. Merchants would travel away from home for months, or even years at a time. The prohibition to marry more than one wife was so that these merchants wouldn’t have wives in multiple ports.
3. As a follow-up to 2 above, a man couldn’t divorce his wife against her will. This was to ensure that a man who was far from home for extended amounts of time wouldn’t just write a “Get” for his wife so he could start with someone new in a different locale.