You don't necessarily have to know what you want to achieve with a piece of work. Some artists do, some artists don't. I vacillate between the two, actually, depending on my medium. And now that you list your influences and interests, I can completely see them in your work, it's really cool, and interestingly made the work resonate with me a bit more.
On to a critique of the work: one thing I would mention: I don't think the background, or "wall" markings need to be so uniform across the page. If you vary them more, with more gaps of white, it will create more movement around the picture, and will have the effect of making the solid, more blocked in spaces stand out more. ... If that's what you want. :) I know that when I did pen and ink work, I had this need to cover the page more uniformly, which actually made the piece more static. Additionally, it could help to lay on some more black in some areas, to move the eye more dynamically as well.
SO...on to more thoughts about all this...it's kinda long so I ended up separating it out a bit....
See, a lot of critiquing is about saying not "oh that will make x y or z "better"" but is about saying "this change will bring about such and such result." And the question is, do you want "such and such result." For example, I recall someone mentioning that the skull looks a little "cartoonish". In the creative art world, this is not a judgement call. The question is truly, were you aware that it is cartoonish? Is that the effect you were going for? Yes? Perfect! No to both? then perhaps you want to change it. Or perhaps you like it that way.
I understand about the yes men. I think that is the one major benefit of having taken art classes. It teaches you to critique art work, and also TAKE criticisms without it become personal. Generally the goal is to get away from phrases such as "I like x y or z" Or, at the least, figure out WHY you like them, so that technique is understood. This can be taken to an extreme, of course; It's part of the reason why art history books can be such verbosely dense to the point that they make little sense. I will never forget the description I read: "space where human refuse heap goes to be discovered" or some such (plus like 15 other words). What did they mean? City garbage dump. I mean, really?
Or perhaps all I wrote is just too much analyzing of art, which is totally cool, too.