Why no pitch angle in observations space for OmniIsaacGym locomotion tasks?

Autonomous Machines Robotics - Isaac Isaac Gym
1

Hello,
does anyone know why the pitch value of torso is not added to the observations space for OmniIsaacGym locomotion tasks?
Relevant code can be found in LocomotionTask.get_observations() of omniisaacgymenvs/tasks/shared/locomotion.py.

    obs = torch.cat(
    (
        torso_position[:, 2].view(-1, 1),
        vel_loc,
        angvel_loc * angular_velocity_scale,
        normalize_angle(yaw).unsqueeze(-1),
        normalize_angle(roll).unsqueeze(-1),
        normalize_angle(angle_to_target).unsqueeze(-1),
        up_proj.unsqueeze(-1),
        heading_proj.unsqueeze(-1),
        dof_pos_scaled,
        dof_vel * dof_vel_scale,
        sensor_force_torques.reshape(num_envs, -1) * contact_force_scale,
        actions,
    ),
    dim=-1,
)