I certainly can’t believe that you are convinced that the pilots on that ill-fated Air France flight were doomed because of incorrectly reading airspeed indicators … are you?
No, on the contrary... You got this all backward. Had they known a normal pitch value for their aircraft (I mean a SET NUMBER, those that you oppose so much upon!), we would never have heard of AF447.
20 degs pitch is not normal in 37000 feet. That is why it's good to know normal pitch values for a lot of different situations. And no, not exact values that require a calculation. Like 5 degs and 65% for a 737. No matter the weight, this will keep you flying above clean speed, without exceeding any other limit at normal terminal altitude. Or 12-15 degs pitch after T/O. Or 1 deg 60% for flaps 30 on a 3 deg ILS.
Knowing such approximate values, not only help if your airspeed is unreliable. It also help to recognize situations that are out of the ordinary and correct accordingly. Like THY in AMS, having 15 degs pitch and idle on an ILS is not normal, to take an extreme case.