Any model that gets rid of these frees up a huge swath of capital and work from society, and can use that work elsewhere. Of course, that is easier said than done.
Each of those are companies worth billions of dollars that could be instead used to lower the individual cost of providing health insurance.
As you say, this would of course be unsavory in some respects as those companies employ a lot of people. It's not a very economically productive industry though, the main output seems to be consuming patients' and doctors' time, causing financial anguish, and causing stress among people as to whether or not if their condition will be covered.
(Medicaid & Medicare claims processors do the same thing. Medicaid claims processing is mostly handled by private, third-party insurers now, and seems to be able to do so more efficiently and cheaply than when it was being run directly by states; the savings is mostly in the area of catching fraud.)
Medicare is much cheaper because they have fixed rates and hospitals know what to bill.