The CQB ARMA 3 is much better than Arma II is a certainty, however, some improvements are needed.
A) Place a door is always problematic if we aim left / right and our little character be stopped probably a collison weapon / wall however, a smart soldier lowers his gun IRL if it interferes, automatic way to do this or remove collisions would be better.
B) Not to mention the problem of unbreakable glass, squatting positions are problematic, it is not sufficiently high to shoot through the windows / obstacle and becomes ridiculous when it lacks a few centimeters, an automatic adjustment (like red orchestra 2 ), or an increase in the height positions would be better.
C) A little furniture or covered in buildings is a plus for the immersion, and tactics, and at best a procedural generation of interiors for variety and surprise (but be careful pathfinding and spawn units)