Perhaps it seems obvious, but I couldn't find a plausible reason why they do so other than evoke negative emotions among passengers and crew.

  Could be another reason(s) to do so?

For example, Flight Number MH370 was retired as a "mark of respect" for the passengers and crew.

Interestingly, is there any case where an airline company reused a retired number for whatever reason AND/OR certain circumstance?

Perhaps it seems obvious, but I couldn't find a plausible reason why they do so other than that it evokes negative emotions among passengers and crew. Could there be other reasons to do so?

For example, flight number MH370 was retired as a "mark of respect" for the passengers and crew.

And out of interest, is there any case where an airline company reused a retired number for any reason or in certain circumstances?