Yeah I know this is stupid, but I am doing it. Here are the 5 basics I think make up a good moc.
A Theme Throughout The Moc
The moc should have a theme that you can see throughout the moc, to make it more cohesive or something.
The Weapon Should Help Represent The Character
actually, I don't think I need to explain this one.
A System For The Colors(if that makes sense)
The colors on a moc should be broken up into 4 categories, bone base accent and metallic, I feel that a moc at most could have 6 colors before feeling way too cluttered. Each color should also have it's own sort of texture to it.
The proportions need to actually make sense.
This is a bit hard to explain, but I will try(again). A Bionicle Character's limbs should be made of the same placement for the colors. For example, if a moc has the "skin" colors on the lower arm and metallic colors for it's shoulder, then it should have metallic colors on the thighs with the "skin" colors on the lower leg. The same thing applies in an asymmetric moc. For the torso, just try to do something that fits with the style and all the colors are properly placed.
Hopefully my stupid system actually helped you(it probably won't), if it does, I would like to see some of the new designs you create!(not that anyone cares enough about me to do anything like that)