No, I don't need the devs knowing how quickly you can blaze through some of those "20 minute" missions.
They already have access to that information anyway, that's why some missions don't qualify. If too many people blow through a 20 minute mission in less than 20 minutes it will no longer qualify.
This would just be providing us with more information, which I agree we could really use. At a minimum having average play time would be very helpful.
But in addition to that if we could have some basic statistics like average play time, low play time (average of the lowest 10% of play time only), high play time (highest 10% of play time only), as well as the number of people who dropped the mission, and number of people who have completed the mission (right now we can only see number of reviews which probably under counts a little bit), and maybe the average level of the people playing the mission.
Maybe they could have number of times played per day or something like that, too.