Government has a history of conceding only just enough of a piece of a right to mollify the uppity people waving torches and pitchforks.
A wide national public-opinion campaign would be needed to knock a hole in qualified immunity because every cop union and apologist under the sun would come out against denting qualified immunity.
If only a few groups tackled the problem at the legislative level, they might achieve some dents and dings around the edges of qualified immunity. Maybe the ACLU or a coalition of rights groups can tackle it the way the attorney in Heller did--by looking for very good clients against who it was very hard to argue. And, then maybe set up a circuit split to get SCOTUS to handle it.
But, yeah. Its backwards. The cop can do anything that isn't prohibited by clearly established rights, rather than the cop can only do what he has authority to do. He gets to make up his own authority to poke through the loopholes as he goes along, rather than operate within the authority he was delegated by the people he was supposed to be protecting and serving.