Thanks all for the replies so far. I'm coming at this from a viewpoint of questioning why this standard question is asked, and who it benefits versus the interference factor in handling a real aircraft emergency by the crew.
In almost every single tape I've heard (and the EI example linked above is a great exception), the crew don't have a ready answer to the questions, and it places a sometimes significant strain on the workload level.
Again, talking about a 737 type operation, one could argue that the Airline (Flight Ops) have the numbers for Souls on Board, and probably also a good estimate of Fuel Remaining. So why not call them instead?
From the incidents I have reviewed there is a pattern of distraction during almost every emergency, which is really interesting.
1. Crew declare Emergency or Mayday.
2. ATC ack, and immediate start into an Instructions, Suggestions and Questions list.
3. Crew repeatedly plead for ATC to stand by. "Stand by", "We'll call you back", "We need a few minutes here", and so on.
On the Souls and Fuel question - as an ATCO, I can tell you that I have no need to know either. So, it's for the Rescue guys.
For fuel remaining - if a 767 is landing soon, I'm curious what the difference is from a fire fighting perspective between an aircraft with 1 hour of fuel remaining, and an aircraft with 10 hours of fuel. What would you do differently as RFF with information of 1,2, or 10 hours of fuel? A good sized aircraft landing soon is going to have a good amount of fuel on it.
I'm really questioning whether knowing if that's 10 tons or 50 tons, or 1 hour or 10 hours makes any difference?
I'm sure some will say that "for a professional crew" it's easy to glance at a Fuel Totaliser and a Loadsheet and give that info - but my belief is that in a real emergency, that's actually quite a big distraction, especially in a critical situation like engine fail on departure.
Any more thoughts on that?