I like my plastic guns. Have you ever left a steel framed gun on a table in the sun. I promise you'll ruin the finish when you drop it after about a second.
I will concede that steel guns look better and higher quality (by and large) than plastic ones but they aren't necessarly better. For the average Joe who leads a life outside of LE and carries the usual assortment of everyday crap (keys, change, cell phone, Leatherman, etc.) do you really want to add the weight of a steel framed gun to your Dockers? Plastic guns give the option to still carry wonderful amounts of firepower without carrying a brick (weight) around.
Carry what you like, that's your call, but cost isn't the only reason for plastic guns or anything else for that matter.