Whatever the scope of the LEO's duty, they should not be granted "superpowers" or be any more immune to legal action than a doctor or a pilot. Claiming that it's so, simply because it's a dangerous or unpleasant job isn't a reason for legal protection, it's an attempt to tug at emotional strings. Nobody got drafted into law enforcement, it's choice. Granting LEOs special protection from legal action removes rights from citizens to pursue justice in the legal system, plain and simple.
Where did you fail to read that cops can STILL be sued if a civil right was violated? And yes, I know the person suing has to prove a) the breech occurred and b) that said breech has been found to be a breech by case law. Point A is a lot easier in this day and age and point B should be able to be done thanks to the ACLU suing for millions of types of civil rights cases. Qualified immunity is not a "superpower", its a protection that allows cops to do their jobs and not get sued for it if they do their jobs lawfully.
The argument you present is just as bad as the anti-gun nuts when they talk about suing gun manufacturers.