A lot of the post WWII Boeing manuals referred to takeoff and landing techniques from that era. Even to rotation techniques from the Dash 80 were incorporated into manuals up through the 80's which did not apply to better performing aircraft.

Rotating a fully loaded -900 with derated thrust to 24k at 3 degrees per second to 15 degrees nose with an OAT of 38 degrees will result in a tail strike.

FCTMs need to be updated to meet actual handling and performance for the the respective aircraft to which it applies rather than generalizations as they were in the 80's and even 90's for that matter.

I think this is what has driven it. The longer aircraft make it more critical.
When they decided to make longer and longer versions things like spoiler deflection became important so they have had a wee re-think.

Crosswind landings, and then takeoffs, at Dusseldorf.

Best takeoff, least amount of downwind drift on rotation, is a 767 at the 5:50 mark.

Condor A320 shows flight control inputs(zero) until rotation. A slight roll input to the right is obvious at rotation. Guten job, jungens!

Crosswind is approximately 30 knots with higher gusts. Control inputs for crosswind on takeoff, if any, were very slight. :D

Takeoff with light quartering tailwind
 

The description of the condition is "light ......" therefore, why bother
about aileron setting ? Once the relative tailwind component is overcome, the take-off will be like any other EXCEPT it will be a longer roll.

If it were a strong tailwind quartering component, I will invariably
elect to taxi to the other end of the RW and take off into a quartering headwind component.:O