Newbie artists tend to make up excuses for the things they don't know how to, or want to draw or put effort into, which is why there's plenty of pictures out there of characters who have their hands behind their backs or in their pockets, and if asked, they also would probably say something like "I think it looks nice", "That's just the pose i wanted for my character", etc
But there are a few other issues with your image if you don't mind the criticism;
- Like, why does this girl have a shotgun shell in her hair, but she appears to only be wielding an uzi?
- Her breasts are almost as big as her head, and they go too high up on the torso, they should start at the corner where where the arm starts (around the pit area, basically), not halfway up the base of the arm
- Her arms are twigs but her legs are E X T R A T H I C C
- Her pose is kind of awkward, it's almost like she's falling over, like that scene from the Matrix where Neo bends over backwards to dodge some bullets in slow motion
