After going through a series of randori drills based on releases recently, I asked if anyone discovered or noticed anything interesting. One shodan commented on how amazing the effect engaging the wrist had on uke as he grabs, whether cocking it up, or curling it toward you.
Yes, indeed! It is amazing how it can disturb his whole frame, his direction, etc.
But here's an interesting experiment you might try (per, as always, Lowry Sensei). Try leaving your wrist absolutely relaxed, without engaging it. Until, that is the very end—then engage it. I think you'll find it has an interesting effect as well!