Nowadays, there is really no incentive to bowl fast. We look at the shot selection of a modern day batsman and compare it to shots played years ago, and we'll see a drastic difference. Players know how to handle express pace, they are able to use the pace on the ball and dispatch these 150kph bowlers with great ease.
Back then, primarily looking at the era where there was only one ball per ODI, you needed a guy on your team who could reach high speeds to get that ball to reverse when it was old. A 130kph bowler is incapable of generating the reverse swing required to make him lethal with the old ball.
However, with the new regulations in place, ICC has literally saved these 125kph bowlers and provided them with a great pathway to elongate their own careers.
In general, we've basically seen fast bowlers adapt to the demands of the game. Why should one bowl 150kph when one can bowl 130kph and have the same likelihood of success? There is no incentive to put that much effort into bowling fast, and hence, bowlers instead use that time to really figure out the length they want to bowl.
