I totally agree with beer drinking from a glass being superior to drinking straight from the bottle or straight from the can. But, we've all consumed beer right out of a bottle and/or a can. Think of being at a picnic or somewhere where it's not always convenient to put your beer into a glass.
If I'm at a picnic, and I stick my hand into a cooler full of bottled beer, canned beer, and ice cubes, then I'm pulling out a glass bottle of beer, instead of a can. At that point, I'm not thinking about the benefits of a dark can vs. a clear glass bottle, etc, etc. I just want my lips on smooth glass rather than metal; plain and simple. A person is always not necessarily trying to create the perfect environment to consume a beer. If you're at home drinking, then yes, use a glass.