There was a lot of conservative panic about the ERA. Rather much like the panic about gay marriage. If Women had Equal Rights we’d be forced into co-ed bathrooms, PE classes would be required to have co-ed dressing rooms and showers, and women wouldn’t bother having children and go into the work force…and OMG think of the family!
Edit: I forgot to add another argument was that the ERA would allow for gay marriage and strike down laws against homosexuality.