I agree, if they knew rain was forecasted (this is 2013, weather forecasting is both easily obtainable and reliable 4+ days ahead of time) they should have sped up the early rounds/qualies and got more matches in, so in the least they could have been in the semis by now.
If they had to take a day off because of rain, fine, but with just a couple of matches to get in, it would be reasonable. Instead you have a scheduling mishap and a bunch of exhausted players to deal with.
Instead they just ignored that it might be a problem and now they have an issue.
I think it's cause of commitments made to networks that quarterfinals, semifinals, etc. have to be played on certain days.
They pay a certain amount for certain rounds to be broadcast on certain days and tournaments can't back out on that deal, if at all possible.