No, what has changed is that with mob families you had ongoing, constant operations where, if you missed one "window of opportunity," you could get a warrant and get them later.
With terrorists, your windows of opportunities are often measured in minutes, at the costs of thousands of lives. Indeed, if a dirty bomb is set off in NY, you won't go there for up to 30 years (for an excellent look at the reality of this, see a British movie called "Dirty War").
The fact is, the court---even the one that the international secret wiretaps should go to---is way, way too slow.
Perhaps what is now needed is a new, rotating 24-hour "court" consisting of a judge who is actually IN the NSA every minute of the day who can instantly approve these taps.
There is a three day window for the Government to go to F.I.S.A for a warrant in cases that require immediate attention. I think that is more then enough window. The only reason to avoid a secret court warrant in such a case would be if the domestic wiretap was done absent probable cause and the wiretap itself failed to produce probable cause for the Government to have done it to begin with.
How can you ask a court for a warrant for a linetap that you have already done that produced no probable cause for doing it in the first place?