Most modern touch screens in portable devices are made of glass.
This glass often breaks if accidentally dropped. Also, it is very reflective, making it difficult to use in strong light.
I know that touch screens without glass exist. For example, the multi-touch screen on my e-ink e-reader has a plastic front. I remember many other examples, such as the personal in-flight entertainment systems on many airplanes.
What are the reasons that most modern portable touch devices come with a glass panel on their fronts, rather than plastic or something else?
The cracking of glass seems to be a pretty big problem.
Edit: I've seen a lot of cracked touch devices, and it's nearly always only the front panel that's cracked. The actual display is usually fine underneath. Even the digitizer usually works perfectly.