I'm an avid fan of metal minis, but have no problem about using plastic figures in a game, especially when there are a number of gamers in attendance with no respect at all for another gamer's stuff. I've had too many figures dropped, and a couple of HA buildings take the plunge to the floor, usually followed by: "I didn't realize it was so heavy".

Among the positive points of metal figs is that you can strip the paint and redo them at some point in the future. Many of my earliest figures are on their second or third paint job, since my painting skills were rather primitive when I started (now they're only "slightly" primitive).

Some plastic figures actually have detail comparable to metal, while others are more like "blobs". Unfortunately, your typical pre-painted minis tend to lean toward the latter category.