- Widmore knew a war was coming to the island. - He knows if MIB escapes the island, they'd all cease to be. Even though all he knows about MIB myths, stories etc..
- Faraday studied Dharma and his journal now contains everything he has ever learned about them. Why was he learning in the first place? Because Widmore needed him to research in order to help him with the upcoming war.
- Eloise knew Desmond HAD to break up with Penny, go to the island, push the button or "god help us all"
- Widmore's secondary protocol indicates he knew about the Orchid and that Ben would be going there. They know more than what's in Faraday's journal.
Someone will be going back in time, maybe Desmon, or Widmore himself. In order to provide his past self with knowledge of the future.
If not time travel then at least Desmond's ability to flash back and forth. That's most likely why they are looking for pockets of electromagnetism.
I'm also guessing there are more pockets since Widmore knows about the Orchid and most likely knows about the swan.