Poor spool-up response is generally overrated as a safety issue; the often quoted 6-7 sec is probably the 8 sec certification requirement to achieve ‘landing-climb’ thrust (usually TOGA) from a low power setting (CS 25.119).
Adequate thrust response is available during the approach and landing. Most approaches can be controlled with changes of only 2-4% N1, and this should be sufficient to prevent a sinker during the flare.
One of the tail strike problems is that the sinker may not be recognised; another is the habit of relinquishing control of thrust during the flare – selecting low thrust/idle early or asking the other pilot to control thrust so that a two handed landing flare might be ‘finessed’. These actions may result in the handling pilot attempting to control the combination of speed/touchdown position during a ‘sinker’ with pitch only, usually resulting in a high nose attitude, whereas a small thrust increase might soften the arrival.
Re “Nothing wrong about landing at say Vref+30 (or 40).”
What an appalling statement given to number of fatalities in overrun accidents this year.
Touching down with excess airspeed in many aircraft may prevent the main wheel air/ground changeover working, thus preventing deployment of lift dump/spoiler, thrust reverse, and probably operation of antiskid/brakes. In these circumstances the “knowledge of performance, within reason, or experience – what you say and do” will not prevent an overrun.