"Because written this way it has the semblance of officialness, of generalness."I agree with you. Moreover, there's very little chance of any agreement about this in the foreseeable future. Those who believe that plaintext is God's gift to emailers will never change their views. They've held these views for many decades, so there's precious little chance of them doing so anytime soon.
We've seen this all before in many other endeavors both technical and nontechnical. Those who wrote with quills and fountain pens said that writing would go to the dogs if ballpoint pens became commonplace.
Fortran programmers resisted going from upper to lowercase (even now, this modern browser editor has a hangover from that long gone era as it automatically converted 'Fortran' to uppercase as was the once custom). As a longtime Fortran programmer, I'd suggest that if decisions about the human-computer interface were left to my kind then we'd likely still be using uppercase ASCII and telex machine would still be fashionable although perhaps considerably faster.
As is usually the case, there's often some truth to the arguments and promoters of a cause buttress them up with historical usage or precedent so as to strengthen their case. Making their arguments sound credible is an essential part of convincing neophytes and potential converts that they're right.
I'll briefly go back to the fountain pen example for a moment as it's analogous to this case and it's simple and easy to understand. There's considerable evidence that when the ballpoint pen overtook nibbed pens a little after WWII that writing did in some ways go to the dogs but the ballpoint only shares part of the blame, things were much more complex than it alone.
I have some authority in saying that as I'm a regular user of fountain pens and I own quite a number of them. Moreover, my writing is much less sloppy with them than when I use ballpoints not to mention the fact that I actually prefer writing with a nib as it provide much better haptic feedback than do ballpoints. There's little argument about that and the evidence is easily demonstrated by examining the writing of current users of said pens.
That said, that's only part of the story. There are also other reasons for why writing deteriorated at that time but it's off topic so I won't go into specifics. However, the relevant point with this example is that the promulgators of nibbed pens only promote their benefit - that of better handwriting. What they omit and never tell you about are the many disadvantages that nibbed pens have: ink gets everywhere, they're messy and time consuming to fill even when using ink cartridges - and probably the worst of all: take a fountain pen on a plane trip and the reduced air pressure forces ink out and all over one's shirt pocket. Right, there couldn't be a worse place for that to happen. And it happens frequently (I know from experience).
Back to plaintext email, it's what its promoters do not tell you about that's the real problem. The list is long but there's little point detailing them all here except to say that two stand out. If images and tables cannot be included as inline information then either they're likely to be lost or misplaced and second, that having to encode and transmit them separately by other means is both time consuming and error prone even if done within the same email client.
Moreover, plaintext doesn't have the range of glyphs and or the means of displaying them so that the presentation of the message information is simple and easy for the average nontechnical user to understand.
Try sending math equations in plaintext and you'll quickly get the 'picture'. Yes, it can be done but it's also messy, time consuming and error prone.
Things that are noticeable about the promoters of plaintext: they're often programmers or those who are experienced in abbreviating messages, they talk in acronyms and understand complex concepts even though their presentation may be poor, and thus they've little interest in presentation for the sake of clarity.
Unfortunately, these attributes are so often what ordinary users lack and it's specifically why big companies such as Microsoft use HTML email. Making software easier is supposedly part of their plan even if they often screw these processes up during deployment.
Like you, I like HTML email, however I'm still critical of it for the reason that at this point in its development it still does not have sufficiently well developed formatting to do what I want to do. For instance, no email client is yet capable of inserting math equations into email with ease.
My philosophy about email is very simple: a user should be able to insert into a message any type of information that can be printed in a book or drawn or scribbled on paper by hand and it should be transmissible to the recipient without any loss of formatting. QED!
Right, we aren't there yet and this view is the antithesis of the plaintext philosophy. Nevertheless, that's what eventually will happen whether the plaintext-ers like it or not.
A final point: you'll note that plaintext-ers are always whingeing about users who cut-and-paste from word processors and web pages and that the info gets garbled in the process; well, they've a valid point.
However, this has nothing to do with the issue that email presentation and formatting should be as easy and as versatile as is possible. The fact that most email clients are woefully bad - in fact outright disgraceful - is a separate issue altogether.
Moreover, I'd suggest many mail clients would be in a much better state than they are at present if the plaintext-ers weren't sabotaging their development. After all, many of them have actually developed mail packages and they give little or no priority to HTML messages not to mention their fervent propaganda in favor of plaintext email.
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Edit: this plaintext email story is not the only one to appear in the last day or so on HN about email content. The other, however, took a diametrically opposing view to this story as it discusses various ways of maintaining accurate CSS formatting in emails - now that's one hell of a jump from plaintext messages.
That story only demonstrates that the gap between the plaintext-ers and those who want advanced HTML formatting is as wide as ever. After reading it you'll likely realize that ultimately plaintext-ers will have very little chance of winning against strong commercial pressures that want better formatting within email.
The link below is to my comment and deals with many of the issues mentioned herein. Therein, I use Thunderbird to demonstrate some of the many problems with current email clients.
Incidentally, as that story was earlier I wouldn't be a bt surprised if this plaintext one was posted as a countermeasure to the former.
https://news.ycombinator.com/context?id=32807489.