Thermoplastic-based touch panels: why not?
The normal process for applying ITO is vapor deposition: like 'fogging' a mirror with steam, but using a boiling metal alloy. The challenge in doing that with thermoplastic would be not melting it in the process. (There are some references on google to doing this at room temperature with a plasma instead, though).

Recent advances in glass hardness mean that 'gorilla' glass screens are much less prone to scratching and chipping than acrylic (which in my experience scratches almost immediately). They are more brittle rather than flexible, but as long as the screen isn't bent that's not an issue.