Then why does he reply so snidely whenever anyone says anything about him being a robot?
Yes, Fassbender's performance is what delivers that message and question, but it's damn obviously from the dialogue that he didn't just throw that in himself.
I think Shaw's arc was explained with just enough depth that the remaining questions kept her motivations intriguing.
I do agree with Vickers' story not being delved into enough. That strikes me as something that got lost in the editing room.
I don't think you really need to explore it in depth. If you were to, it would make the movie drag. I will say, it did throw
so many concepts around throughout the film, that in order to keep the pacing right, it had to limit just how introspective it was.
At the same time, that's not always a bad thing. If you go too far with the explainations, you end up with movies like Batman Begins where the word "fear" is said eighty million times.
Our motivations towards creating robots are - sure - but it raises questions about the Engineer's intents.
Sorry, that doesn't even make sense to me.
His foundation and backstory are pretty evident in the film (and if you need it handed to you, there's an entire website detailing it.

), yet his exact motivation is still a question. Yes, it has been done before. But, for me, I've yet to see it done in the particular way they did it in Prometheus. This is my personal preferences, but I'm a fan of that type of archetype that Weyland represents.
I would like to mention at this point, my whole goal was to show that the film had depth. The fact you admit that these questions even exist prove it had depth. Now, you could argue that it wasn't done in a quality fashion, but you didn't. You just said it wasn't there at all. More hyperbole.

I find cliche comes from the conclusions not the questions. And they didn't answer the question in any cliched way, which was a big win in my book.
Her religion was mentioned numerous times in the film.
Again, that statement right there, I can't vehemently disagree with. Because it's an opinion that I can understand (disagree with, but still understand). But again, if that's the case, I ask for the
why to it (which you have done in this post, don't get me wrong).
No, not at all. It's deep because I felt their quotes about religion, science, and creation raised questions and intrigue in my own head.
If it they were as meaningless as you infer, I would've just walked out of the movie theater and forgotten about them. For me, that didn't happen at all. It was the exact opposite, actually.
Shouldn't that be hundreds or thousands?