Why aren't we using LLM's to chemically redesign old drugs?

I was fooling around with Cisplatin, a chemo drug that made testicular cancer curable. Then I was like, I wonder how Chat GPT would improve this drug. It tried. Is this a good idea?

"The best chemical improvement is unlikely to be “a stronger cisplatin.” It should be a less reactive circulating molecule that becomes ordinary cisplatin only after tumor uptake. My preferred candidate is therefore: A neutral, asymmetric cisplatin-based Pt(IV) prodrug with one stabilized albumin-binding axial ligand and one reduction-released glutathione-synthesis inhibitor, with the axial electronics deliberately tuned to prevent premature blood reduction."