I've been using Foundation for Emails[1] for the very small number of emails that I've worked on which required more than just a list of img tags, and I really appreciate it for existing because HTML emails have been stuck in ie6 web days.
I hope the upcoming EU Accessibility Act will be enough for many organizations to finally make their emails accessible. I disable images by default in my email client, and some emails are pretty much empty without them, without providing any alternative.
Isn’t the whole point of sending emails to get the recipient to read them? If the recipient can’t read them, you wasted that money and captured no value. Possibly negative value because you just reminded the recipient of how annoying your website is. “Oh right, that vendor with the full-page modal that I couldn’t dismiss, or was it the vendor that had a pretty site that turned gray three seconds after loading for not discernible reason and wouldn’t let me click anything after that? I’ll just shop at Amazon next time even though they’re more expensive and vaguely evil.”
We have a html and txt template for each email we send. It's not exactly double the work, but it's appreciated by some of our customers.