Yeah, one game I had a puggie bitch at me about, "Playing Mei and not ice walling, lol noob" but really...in complete pugs where there's little communication and even less listening, ice walls are just going to end up fucking something up as often as they help.
That and I always wonder why Mei players on defense put up ice walls in front of the payload. It doesn't stop the payload, and aren't you just helpfully covering our advance for us?
I think the only time I really use ice wall in pugs is to do annoying shit like pin myself in a corner on defense points and hold it while my team rezzes or something.