Not all HTML emails are image heavy monstrosities. There is a lot you can do with HTML/CSS that makes the message easier to consume and more impactual without using a single image.
I feel like HTML email design lags about 5-10 years behind website design. Some of that is the limited feature set, but I think more of it is the lack of design attention its given. It seems like most of it gets generated by a marketing department using some crappy marketing campaign templating software from a decade ago with little to no thought to how the output is consumed.
I disagree with your argument that email lags behind web design due to pack of effort. Have you ever tried to code a HTML email like you would code a website and looked at the result in email clients? Do this once and you'll see what I mean.
Actually I agree with this, perhaps we're just debating cause and effect. Developers in my experience do hate putting together html email due to the wonky client constraints and as a result often say to marketing "its a mess, I don't want to touch it, find a e-mail making program / service to do it".
But is that the cause or the effect?
Rather, are email clients still a mess because developers don't have much interest in topic? Even gmail has strange html/css rules, if google pulled that with chrome there would be pages of developer outrage here on HN, almost no one seems to care about gmail's html rendering, or enforcing a spec/compliance for email clients, developers are apathetic about it.
What I'm saying is, developers don't like working with html email because its a mess, but its a mess because the development community as a collective doesn't seem to care about it, at least not enough that there is a concerted effort to fix it.
"almost no one seems to care about gmail's html rendering"
Addressing that specifically, a couple years ago when Gmail's HTML rendering was even worse than it is now, the Email Standards Project started this http://www.email-standards.org/blog/entry/getting-some-gmail... to try to embarrass Google into improving the rendering. It sorta worked.
And why is it generated by the marketing department's crappy software and not the engineering department? Because no-one in the engineering department wants to program like it's 1999!
I feel like HTML email design lags about 5-10 years behind website design. Some of that is the limited feature set, but I think more of it is the lack of design attention its given. It seems like most of it gets generated by a marketing department using some crappy marketing campaign templating software from a decade ago with little to no thought to how the output is consumed.