I've probably field dressed over 50 deer with a knife, and just 2 with the Wyoming knife. It is not necessary, but makes it a little easier to do a clean job with a bit less intense concentration. Like you, I remember the time I made an "oops!" with a knife into the intestine/bladder. Not pretty in 10 degree weather and falling darkness!
Last Christmas, I received a a "Swing Blade" knife by Outdoor Edge. It has a drop point blade that swivels around to a very interesting gutting blade. Not a hook, but a design that looks like it might have real possibilities. I am sure the steel is nothing to write home about, but it looks like a neat approach to handling an old problem. We'll see when (if) I kill my first deer this year, but it might be worth considering...