What happened to me, and possibly what Oldrubline is concerned about, is that my release became jerky and my accuracy decreased because of it. I was using a non-anticipatory psychotrigger, similar to a clicker, and thought I was releasing subconsciously when the trigger went off. I agree that generally it is a good thing to release automatically when the trigger goes off, without thinking about it, and that is what I was trying to do. However, what I think happened was that my release ceased being subconscious without my realizing it, and I began releasing the arrow by consciously opening my fingers when the trigger went off. This would cause minor deflections in the arrow path; it was frustrating to me to see the arrow going off in a slightly different direction than I was pointing, even when my alignment and back tension were okay.
Then I read a post by Arne where he recommended allowing your fingers to relax naturally, both to insure that you weren't consciously popping your fingers open, and also as a means of achieving a surprise release. I was able to learn to do this, and my annoying deflections disappeared. The amount of actual time required to allow your fingers to relax naturally isn't much different from the time required to pop them open, so it isn't like you're going to be holding the arrow back at full draw noticeably longer after the trigger goes off than you already do.
If you truly have a subconscious release and it's working well for you, then fine; keep doing it. But if you're really just popping your fingers open at the trigger, then it could be a cause of inaccuracy.