If only because it's simpler, so it might have been more fully and consistently supported (and it's not a security nightmare).
If everyone could just agree on a safe subset of HTML for email then that's all we would need.
text/enriched was basically proposed as an interim result for richer text than plain text back when HTML email was controversial.
There is a more-or-less defunct community group at the W3C about building an HTML email specification. In practice, the elephant in the room remains Outlook, which uses the same HTML engine built into MS Word, which, IIRC, is built on IE 5.5.
In lacking most of HTML's complexity and features, it lacks its security issues, too. And in being very small, you can reasonably expect the whole spec to be implemented.
But yes, with a very strictly validated, very small HTML subset you could get a similar effect. At that point, though, why use HTML?
Color
causes the affected text to be displayed in a specified
color. The "color" command requires a parameter that is
specified by using the "param" command. The parameter
data can be one of the following:
red
blue
green
yellow
cyan
magenta
black
white
or an RGB color value in the form:
####,####,####
where '#' is a hexadecimal digit '0' through '9', 'A'
through 'F', or 'a' through 'f'. The three 4-digit
hexadecimal values are the RGB values for red, green, and
blue respectively, where each component is expressed as
an unsigned value between 0 (0000) and 65535 (FFFF). The
default color for the message is unspecified, though
black is a common choice in many environments. When
nested, the inner "color" command takes precedence.
Odd that it's 96bpp colour, of all things.
1) RGB: #rrggbb (rgb hex) / rgb(r,g,b) (rgb int 0-255) / rgba(r,g,b,a) (as before, plus alpha). In addition, rgb/rgba support percentage values instead of 0-255.
2) red (color names)
3) hsl(h,s,l)
4) cmyk(c,m,y,k)
For compatibility with anything except Thunderbird (which supports all four formats IIRC), stick with #rrggbb or plaintext names. Webmailers are especially prone to filtering by regex (ugh), and stripping out everything they don't know.
I feel like I'm reading Hacker Rehashed News
I'm really pleased that email cannot set a style header and has limited ability to have the email deviate greatly in presentation from other email I receive.
Just playing devil's advocate here.
If you want to show your styles to Gmail users and you have to inline your CSS in every HTML tags you want to alter, which is very ugly and made the email size unneeded large.
That said, we still need to get this sort of thing in Microsoft Outlook, and both that and Gmail really need to support CSS to something of a normal standard, like with say Apple Mail or what not. There's no real reason email standards should be different to browser ones, except with the former not having Javascript included.
There are plenty of reputable email clients that add extra styling to make email look better that are not necessarily spam.
https://www.gaertner.de/~neitzel/mail-policy.html
https://www-user.tu-chemnitz.de/~heha/email.var
The prevailing attitude seems to be "If you can't configure your email client to send plaintext or follow the other rules I've listed on my site, I'm not interested in communicating with you."
Yeah, thanks. I'm doubly ecstatic when the unsubscribe link is in the HTML version and not the text version.
The example they give with a YouTube email. I wonder if they decided to make the change because of internal pressure from those sending out marketing emails.
This way, content using position:absolute can't escape the iframe borders, and the mail gets to enjoy full responsiveness.
Even without media queries, enabling <style> blocks in html emails is huge (google was the last holdout). For anyone developing html emails, this is a nice set of changes.
I don't need any of this fancy.
I'm looking for something that resembles GMail's actual functionality that is currently supported by Outlook and a variety of other email clients. I would just prefer a Gmail-native app because the Gmail app works more smoothly with Gmail than Outlook or any other provider does - particularly around search.