Whether we like it or not, 3As have been, at best, glorified SLs and will remain so forever. After the advent of online booking through credit cards, traveling in AC has become so common and with the existing fare structure and rising operating costs, IR cannot do much regarding passenger comfort measures. As for curtaining, it was more of a nuisance than anything. Privacy in a small space that includes 4 washrooms, 6 doors, gangways, and 72 berths, in my personal opinion, is too much to ask for.