According to an article in the Washington Post, Senat Opens Debate on Wiretap Measure:
...Vice President Cheney said in a speech yesterday that Congress "must act now" to renew the expiring surveillance law and provide telecommunications companies with protection from lawsuits alleging they violated personal privacy rights while helping the government after the Sept. 11, 2001, attacks."
But the question still remains: What type of help were they providing the government after 9/11?
For example: Did this help involve spying on political adversaries of the administration for the sake of helping them pass legislation beneficial to their campaign contributors?
If not, what is to prevent some future administration from 'selling' their warrantless wiretapping power to the highest bidder - allowing it to be used to help some 'friend of the President' get the edge over some political or economic rival?
The simple act of requiring that the government make its case to a court - an independent third party - will help to ensure that the government is actually using the power to wiretap to protect the country, rather than protect the President (at the expense of the country) - or to profit the vice-President (at the expense of everybody else).