The most efficient way to destroy things on the ground is with guided missiles and bombs. An F-35 with a brace of SDBs is going to do a lot more damage than an A-10, both because smart bombs are much more effective on a pound-for-pound basis and because it can get on station much more quickly. A strike aircraft with modern optics it can fly above AAA and shoulder launched SAM range and still engage moving targets on the ground.
The troops like the A-10 because it's loud and impressive and makes them feel like they haven't been forgotten.
Politicians like the A-10, too, because by staving off the ax once again they can make it look like they're doing something to support the little guy on the ground.
The Army brass likes the A-10 because they suspect when the shit hits the fan the Air Force will decide the multi-role aircraft all belong in some other role and abandon the Army altogether.
But none of that has any bearing on the effectiveness of the air frame itself. Not many people realize the A-10 only carried out 20% of the CAS missions in Afghanistan. The A-10 was the bee's knees when it was new and we were worried about thousands of Soviet tanks pouring through the Fulda Gap. But it's not 1985 any more.