yeah, it has been mentioned way back when, but the dreams aren't "dreamy" and stuff is because it's a heist movie and they're trying to trick the mark. It would be like trying to steal a white supremacist's wallet at a clan meeting and going with a crew of blacks, asians, and hispanics.
the instance you really see them intentionally do crazy thing is when Leo and Juno first go into a dream. Even then, she didn't realize it was a dream because that was the intention. When both of them were aware, they were able to change the city around and all that.
about the shooting scene...yeah, that was pretty boring. But Mombasa (from the OST)

dreams that barely resembles anything dreamlike
THEY WEREN'T SUPPOSED TO BE
When the subconscious realizes something is wrong, it should project things more sinister than lame goons with guns as a defense mechanism.
If you were paying attention in
class the introduction, you'd remember that the dream was populated by what the person knows. It's like how Cillian Murphy's idea of Tom Berenger appeared in the hotel section.