baccaman, you're a hero! This is the exact thing I think that pixelation-ers should try to think a bit more of! I mean, we're already the absolutely best art critique forum on the net, but this is kind of a flaw I see, it's like.. we're all striving to accomplish the same kind of ideals, which makes us conform in the end O: A bit.
It's like we're trying to find the perfect techniques and then we try to make others use them aswell, which makes us all conform to the same techniques.
No problem with that, though, really. It's not like there's any chance that we'll loase our individuality, it's just that we give, eh, kind of the wrong kind of critique to people like jack bauer
Anyways!
I think things that really WOULD improve your pictures is learning how to anti-alias your lines. Jonathanofdrain actually made some sweet stuffs there. You should check them out.
I think your images would improve with some more unified color schemes and texture. Achieving texture in pixel art is hard, but there's a lot of ways to go to it.
MY advice would be to try to bring some sepia-toned goodness into your pictures, and some grime and texture, shadows and smoothness. It would clash wonderfully with the perfect perspective you're using.
And lastly, keep the perspective, do your thing. I'm liking it a lot :]
Plus, you've become way better with expressing volume and shadows, just do what you're doing now with the shading, but do it more. You're on the right track!
And lastly a challenge: Next piece you do, try to throw some perspective in there. Working small and isometric is a challenge that i think would fit you very well, even though it's different from your usual drill :]
Good luck!