Image credits: Macdon401, oliko, Ben Balistreri, OEffeO, H.B. Lewis, J.M.F. Oli, Ryan Wood, StephenSanchez
Looking at the concept art world shows multiple "schools" of concept art with completely different goals and opinions about appeal. These differences can be boiled down to a struggle of two artistic forces: construction and expression.
Construction is like rhetoric, and appeals to audiences through accuracy of description. Expression appeals to audiences through purity of design, emotion, or ideas. Construction can be devoid of expression, and expression can override the need for accuracy.
Every school of art uses some combination of construction and expression, but great artists recognize that expressive elements connect with audiences in ways that crude construction can't. But my point isn't to prove that expression is better than construction. In fact, without construction there can be no expression. The reason why Acadamia has difficulty producing good artists lately is because most schools have rejected construction-focused education and focus almost exclusively on expression, leaving artists without the tools necessary for powerful expression.
Rendering this monster's arm with a few expressive lines took some thought, and relied on years of studying anatomy and how to use line to describe form.
Remember though that construction covers a lot of areas of learning, so anatomy and technique won't guarantee expressive ability. The first image shows that a basic knowledge of anatomy applied randomly can result in a hodgepodge of shapes and form changes that aren't terribly appealing. The second image is a lot more clean, fits the wound-up personality of the monster, and has an appealing interplay of shapes and forms that compliment the overall design. These design decisions relied on constructive elements of design being applied to other constructive elements of anatomy and form in a harmonious way.
One last story to make my point. The other day I was trying to draw people and I couldn't get the hands to feel natural. I could imagine what I wanted, but even when I looked to my own hands for reference what came out was awkward. I suddenly realized that I've been coasting for years on a rudimentary knowledge of hands; I'd learned to fake things so well that I'd overlooked some important education. So I pulled out Bridgeman's Constructive Anatomy, spent an hour studying the forms comprising the hand, then attempted my drawing again. That time it came out the way I wanted. Now I've resolved to keep studying hands until I can express what's in my imagination effortlessly.
The moral of the story is: if you're struggling to find expression in your art, your problem might stem from gaps in your knowledge of construction. There is also another roadblock to expression that I'll talk about in a later post.