You're right that most services do send a multipart message with a sane looking plain text version.
The biggest issue with that is when the sender of the email doesn't actually check that the content was converted properly. Most notably, hyperlinks in the HTML get converted to the text of the link and the URL in question is no where to be found.
Even if most HTML emails send perfectly created plaintext versions (and yes, Amazon is great at this), you'll remember the crappy unreadable HTML-only emails far more than the normal looking multipart ones with proper conversion of the HTML to plaintext.
My first job in high school involved formatting and sending out email blasts. Even at that point, I was aware of potential formatting issues and I took care to make sure that the automatically generated plaintext version had all the same content. For that reason, I have no patience for HTML-only emails crafted by grown adults.
The biggest issue with that is when the sender of the email doesn't actually check that the content was converted properly. Most notably, hyperlinks in the HTML get converted to the text of the link and the URL in question is no where to be found.
Even if most HTML emails send perfectly created plaintext versions (and yes, Amazon is great at this), you'll remember the crappy unreadable HTML-only emails far more than the normal looking multipart ones with proper conversion of the HTML to plaintext.
My first job in high school involved formatting and sending out email blasts. Even at that point, I was aware of potential formatting issues and I took care to make sure that the automatically generated plaintext version had all the same content. For that reason, I have no patience for HTML-only emails crafted by grown adults.