The only reason I have observed (I'm being very diplomatic here) for pilots to be reluctant to slow down is when they perceive themselves as being high on profile.
Pilots hate being high and hate speed brakes even more so they use increased speed to correct the situation. Being told to slow down means they will end up even higher on profile, definitely needing the speedbrakes, so they temptation to cheat a little is very great, especially since a speed reduction is not well defined: I can slow down from 320 to 250 in twenty seconds, but I can also do it in 2 minutes...
This is in no way an excuse
