Here's an older story from the Joongang Daily that I have to post in entirety.
(September 26, 2005)
(PIC) Policemen yesterday removing steel mesh from windows of buses used to transport riot policemen. The National Police Agency said it removed the mesh from all 1,131 buses, citing a drastic drop in violent demonstrations as the main reason. A symbol of the military government in the 1980s, the vehicles were dubbed "chicken coop cars," and used both to transport forces and blockade roads. Police said there were 809 illegal violent demonstrations in 1998 but the number fell to 215 in 2001, 91 last year, and only 34 by August of this year. "The buses also give a bad impression to foreign tourists," officials added.
Note: Looks like a positive step, I always found them unsightly, parked as they were at most prominent corners in the city (shin chon, jongro, etc). I would often get the suspicision that something was going down, even if these buses were just parked there for no reason. I wonder if the US embassy is still surrounded by a fleet of them. Hmmmm. Will the buses will still be parked around town, but cageless? Or are they going to hide them altogether?