"His designs are fine"
You are baiting if you believe in your words. I can't take your post seriously sorry. I love to troll users doing the exact same thing you did. However I use coherent arguments through the process.
Many users begin their work with block models because they use the 3d editor as the starting tool. You can't design your mech inside 3d editors because the design process is hampered and fragmented. A 3d modeler is a documentary of your work turned into vector graphics. If the work is not hand drawn or studied in any other medium, the result will be just a juxtaposition of random pieces. The design process requires trial and error, some concrete ideas and a study to a certain approach. What he is doing is a 3d doddle.
3d modeling is a process of documentation where all the ideas are summed up. The documentation requires previous design before the model is being transcribed. You have to model the whole thing or have an idea about the whole concept. His work shows added forms without function. He is using a lot of predefined to put up a model. The process should be inverted. It has to be the other way around. The completeness of the model need to be established first and then work the pieces.
The engineering approach as I said is the correct one. But he needs more knowledge mounting those pieces together. For example there are lots of silly models in Hawken. Some of them are good others are awful because it uses the technique of the "found object art" imposing interpretation over existed pieces. It is a valid way to design but not necessarily gives a good result.
"if you are criticizing the medium he is aiming for or comparing to (Hawken) than it is more a matter of the chosen aesthetic for the game. That is to say mech games have a variety of aesthetic choices that are often defined by their function versus their form."
Learn to read, I never used Hawken as a parameter or standard.
"To say that his designs are "poorly" thought out is kind of a dick thing to say when its clearly something he has put work into and it is clearly something he enjoys."
In the internet, it is always fun to read awkward baits like this one but, that's not the purpose of a board aimed at learning and improving art..
In art you have to be frank and direct. You don't nurture artists. For that you have your mom and your dad that rewards you like a child when you do something good. If you want to make something interesting you have to learn the hard way. There's no other way to improve on your job. If he gets the false notion of having a great job, he will surely is destined to suck. Just look at any design of a mech out there. If you want to reach a caliber you need to demand more within your design process. He has none.
"I think its a solid piece and while it seems like more of a High-Poly model it is necessary for an artist to show that they are capable of thinking in terms of the smallest detail and not just the rough picture."
Obvious bait.
You don't lose your time on the details if you can't have a whole picture of your project.
"Artists do things different ways and in different manners they are more comfortable with. If he thinks he can get his idea down better in a 3d modelling program like Maya, Blender, or Max, than by conventional traditional art means, than who are you to say his approach is wrong."
He has potential but his design process is missing, simple as that. Why? He has no design process at all.
"Most people wouldn't have a clue as to how he arrived where he is with his design and sometimes designs flow better in free space than on paper. It's all about the person and the pen, whether that pen is literally a pen or is some other form of tool."
The result made explicit his deficiencies.
"Just as well its good art and I hope he posts more as well as anyone else who isn't afraid to show off their art. It can be hard when even the artist is too critical of their own work to hear the voices of others."
 
If you make your work public, you have to deal with the heat. Those are your options.
Now let me do this post more pedagogic for him. 
Concept robot:
http://conceptrobots.blogspot.com/
Some examples. These are professional artists so I'm not expecting him to reach this standard. Take years and lots of effort to reach this caliber. 
 
This image is simple but convey a great design with simple gestures. 
 
An additive approach to design with a clear conception of the project. Look at the joints and the skeletal links of the anthropomorphic figure. He decided to solve "joint problems" and "articulations". 
 
This design tries to be more realistic and concrete with the textures on the pieces. The design is "engineered" with current robotic technology. It seems achievable with current technology. 
 
 
Another amazing example of realism and detail. 
 
