Neck shots can be very decieving as far as placement, much more so than the good old boiler maker shot that gives actually quite a large margin of error. I have made them plenty of times with a rifle, but only from a steady rest...and I myself prefer to take only the back of the neck, base of the head from behind, obviously. Not a good shot at all for a bow.
At the same time, I have seen quite a few deer where neck shots missed the bone, and after initially dropping the deer from the shot, they get back up and run. Generally with a bow, few folks go for a "bone" shot, leaving the narrow window for the jugular/etc. which is very easy to miss if you really dont know your anatomy.
A shot not taken is never to be regreted. Dont pressure yourself into thinking you should have taken it. There is never wrong in not taking a shot.