The Space Shuttle was weird and unusual in that it was the only spacecraft ever capable of bringing significant payload back down to Earth. It cost a whole lot of payload up mass to get that capability (every flight had to carry the reentry protection for that huge payload bay, even if you didn't actually need it) and it was used on several occasions- things like Palapa and Westar (STS-51A), Solar Max, and all the SpaceLab missions- but on many other flights the payload bay came home ~empty and all that protection weight could have had better uses.

All that comes home in current spacecraft (Dragon, CST, Soyuz, Shenzhou) is the small compartment with the people in it, and each of them even leaves the "orbital module"- all the fuel etc. behind to be burned up in the atmosphere. (Progress cargo flights burn up, but Cargo Dragon is actually recovered so some amount of cargo can be returned fully to Earth, but its mostly scientific stuff that is coming back in there right now as I understand it.)

The only such capsules available are already being used to return astronauts. There isn't enough spare capacity for returning much else -- and certainly not 2.6 metric tons of batteries.

It's basically free to let the orbit decay. It is hundreds of millions or billions of dollars to return it to earth. It doesn't make sense to spend a billion dollars on literal trash.