Just think what would happen if the rain that has wrecks havoc on the 2014 US Open, like it has this year so far. Instead of screwing up one tournament it would wreck havoc on two of them. In 2014 for the first time in Open history one course will host both the Men's and Women's opens. Pinehurst #2 will do the honors.
While having both of the tournaments at the same site sounds like a great idea for a variety reasons, it does come with its drawbacks. If there would be a delay at the Men's Open it could destroy the Women's Open. Say by some act of god rain washes out a round of the Men's Open and plays gets pushed back to Monday. Then the course crew would have to change the set from the Men's Open to the Women's Open. So the earliest that a women would get a practice round would be Wednesday and it would simply be unfair to just give them one day of practice before they play in the biggest tournament in their sport. By having them both at the same site you are also asking people to spend a ton of money to go see both events.
While the thought was good any delay could cause an issue, it will be interesting to see what happens at Brandon Dunes in 2011 when both the Mens and Womens Amateur is held at the same venue.