I think of manners as an Fe thing. I put 5 but I think I would change it to 6. I wouldn't say that I'm not well mannered but I think I get too comfortable too quick. I'm not as natural with formalities as I should be, unless I'm trying really hard, like for an interview or something. I do feel that generations before us did a better job at this. (The generations before the baby boomers.)
They were less centered in their own success and busy lives and more centered in relationships and each other. I haven't read the article yet so I don't understand the technology question, but I can take a blind smack at it. I think we get too used to communicating via technology, which doesn't require as much skill with etiquette, as manners a lot of times require certain body language and facial expressions. I think of "technology manners" as using capital letters, proper punctuation, and spelling, and full sentences. An email with all the new abbreviations and smileys, lowercase, whatever, would indicate either a closer relationship, and of course you wouldn't email a resume with this type of language. But face to face manners are a completely different thing, obviously. So in short, no I don't think it's less necessary, but it's definitely less common since people get less practice. If that makes sense. I may be off in left field with this, but it's my own idea without having read the article to know what you're talking about.
I work with the elderly and find that having manners goes a long way in my friendships with them.
They tend to open up and feel more comfortable around a young lady with manners, because that's what they grew up with.
Edit: Just read the technology in public article. That is much more accepted than it was even 5 years ago, I think.