Anyways, the reason nobody works on these is probably because our existing antibiotics already work really well, likewise it wouldn't be terribly practical to develop more.
No! No! Bacteria have been evolving antibiotic resistance and things are getting quite desperate, especially in hospital settings. Newer and more potent antibiotics are urgently needed. Methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and multi-drug-resistant Mycobacterium tuberculosis (MDR-TB) are well-known examples of superbugs. The latest are NDM-1 bacteria that have acquired the ability to defeat carbapenems, the antibiotics of last resort when all else fails. And these are failing too. There is an ongoing arms race between bacteria and antibiotics and it has always been so since the introduction of penicillin. The bacteria are getting ahead and we need new antibiotics since yesterday.