Contingent incentives (‘do this to get that’) drive people to focus on the ‘get that’, not the ‘doing this’. In short, incentives serve to devalue the task.

“Fifty pence for doing the washing up” what do our children learn? Washing up is a dirty job.
The psychology literature shows that when a reward is made contingent on an activity, the activity itself becomes devalued. For a thorough summary of the research read Alfie Kohn: ‘Punished by Rewards’.

Among many examples, Kohn cites research on children being ‘rewarded’ for reading with tokens which can be exchanged for hamburgers. When the arrangement stops, so does the reading. They are effectively teaching children to not value reading.

Incentives discourage pride in work. And pride is the most important source of motivation.

Pride is intrinsic motivation: pride in doing a good job; pride in learning. A prerequisite for intrinsic motivation is having control; control over what is being done, control over what is being learned.

People are more motivated when they work in systems over which they have control.

People are less motivated when they work in systems where they feel ‘controlled’.

Command-and-control management assumes people can be motivated by ‘extrinsic’ forms of motivation.