I don't know what year you have to be born in to be Gen-Y (different sources say late 70s all the way to mid 90s). I have found that people my age and a bit younger suck at detecting sarcasm and facetious comments. Especially women. Or maybe I have Aspergers or something.
i'm from '84 and I think the reading messages in meetings/conversation, is mostly not thinking. It becomes habit from using these "web 2.0" devices that you can put others on hold or ignore and not have immediate consequences. But I agree it is rude, and I think they may be exaggerrating the ignorance of the youth.