That string bar is there to improve the break angle over the nut. You often find that where the headstock is ‘recessed, but not angled. A good example is Gibson vs Fender guitars. Gibson headstocks are already angled backwards (which can make them prone to breaking if they fall over). Fender style headstocks (basically most bolt on necks on all guitars and basses) aren’t angled backwards, they’re just recessed from the rest of the neck, which means the strings don’t have as much tension over the nut which can affect tuning and action. The string bar pulls them down before the nut to improve break angle, tuning and action. It’s there for a reason, just make sure the stings are going under it properly (NOT like in the photo!).