If cabin lights are dimmed during night landing so that your eyes will get used to the darkness, why do they let you use the reading lights? Everytime the question of "why do they dim the lights during night landings" pops up, people say that it's to make passengers' eyes used to the darkness if an evacuation is needed (see: Why are the lights inside commercial airplanes turned off during take off and landing?)

However, on every commercial flight I've taken, the flight personnel always makes sure to mention that you can use the reading lights above you if you want, which are powerful enough to compromise your night vision (and that of people sitting next to you).

If the motivation is safety, why don't they disable these too? If anything, they should not be encouraging their use.
That is a good question. It is most likely a compromise. Turning down the cabin lights allows for night vision adaptation for most. Its better to have at least some of the passengers adapted, than none at all. Its a compromise between optimal safety (night vision adaptation) vs customer service (being able to finish reading your Harry Potter book).