If you really don't like with the line, I can see how that may be frustrating that I keep telling you to make it fatter. I think it makes things clearer, BUT it's not good to draw something you don't like.
I can't really think of anything else for making things clearer, but maybe someone will..
Did you try to look to your coloured lineless drawings from very far? I think they are really cool and personal, with a great 3D effect, but the fact the colour contrast is rather delicate and the absence of line make them a little muddy/undefined when looked at quickly or from far. I'm sure there is a way to fix that while keeping your very personal style but I'm not sure how.