[chessturk]

I'm not sure that's an issue by itself. If the prompt is broad enough, a minimum length can be reasonable for essays.

It certainly could be a problem if the prompt was too narrow, or time constraints, or some other factor.

Do you think the correlation by itself indicates something negative/inefficient I'm missing?

[yoz-y]

I think that the required length should be bounded on both sizes and penalised if the paper is either too short or too long.