I find everyone is too timid with shading and contrast, and this is something that just needs to be beaten into a painter's head before they truly understand the concept and purpose. I know it had to be pounded into my brain before it finally clicked.
The reason is looks like too much on the shoulders is because you're looking at it dead-on at the shadows, and not slightly above. It's also because the shading on the shoulder is next to a very bright, nearly white area of the carapace. This happens when two areas with high contrast are placed next to one another; it serves the purpose of separating those areas, and giving each definition, so they don't bleed into one another.
Take into account the angle of viewing before offering such a critical review on my tabletop standard....
In order for white to have depth, and to look good in photos, and from far away, you
must have dramatic shading. If you don't, when you put it under the bright light to be photographed, all the shading will disappear. The same thing will happen when you put it on the table and look at it from 2 to 4 feet away.
And trust me, I'm not implying in any way that it doesn't look good up close....perhaps if you're at Lock n' Load next year, we can put our models side-by-side for a close up comparison and critique. I'd be more than happy to let you pick and examine with a magnifying glass any of my models. I'm not sure how many of the severe critics out there would let me do the same, and offer an extremely critical review.
Keep in mind that miniatures have to have dramatic highlighting and shading, otherwise they will look flat, featureless, and unrealistic.