[Vigilanteman]

Here is a list of reasons:

1. It is intimidating and threatening.
   
2. By being threatening, they invite violence.
   
3. They are overly concentrated in minority neighborhoods.
   
4. How are speech impaired or hearing impaired people supposed to talk through that barrier?
   
5. It denies the locals the same rights to steal as those who live in neighborhoods which don't have bulletproof glass.

[Dr. Sivana]

How are speech impaired or hearing impaired people supposed to talk through that barrier?

There's a metal plate with slits in it that allows sound to pass through.

[tet68]

Those are merely Chicago sneeze guards.