Initially I was very nervous about taking head shots, largely due to the stigma against it that I've picked up on from this site. However since I started head shooting a significant proportion of my annual cull, I have found that the fear is much, much worse than the reality.
The thing that really helps is that there is no "clutter" around the target area. No mass of neck or chest, causing you to have to estimate the precise place to try to place your shot. The target size is no different to that for a neck shot, I don't think, but at least you can see the target!
The eyes of the deer will always be in the same place relative to the point on the head that you want to hit, which is more than can be said for using the front leg (for example) as a guide to placing a chest shot. The leg could be forward or back, or the deer could be slightly quartering. So using that as a guide is an estimate at best. However, use the eyes as a guide to head shoot a deer looking straight at you and you know exactly where to aim, without any guesswork and without any distracting other parts of the deer's body in your sight picture.
If sub moa groups are the norm (as most shooters would have you believe) then there really is no challenge. But maybe they're not the norm? Maybe they're only the norm among the targets people post pictures of? The rest of the targets go in the bin.
If the targets people post on here are to be believed then I know that, compared to most, I am a very poor shot indeed!