Over the last 10 years I have worked with 4 digits worth of people. Managers, sales people, engineers, family members, locals, Western foreigners, Arab foreigners, Asian foreigners. I can't remember a single communication where direct insertion of images was a desired feature. If at all images were in emails because the email clients interpreted adding attachments in image format as part of the emails content (gmail client for instance).
I'd argue that images in emails means that you haven't reached 2017 yet, where there are loads of better options to share images.
I'd argue, in turn, that your experience, regardless of how many people were involved, is divergent from the way in which email itself is moving in the broader market of users.
Images as links to something else, that require an additional step, are an inferior substitute to inline images. Here in 2017, it's possible to build an email that includes tables or screenshots or other rich media that exist as part of the email itself.
This is commonly viewed as a benefit. 20 years ago, I, too, was resistant to the idea that email should be something other than plain text, but I was wrong. That ship has saild. Email today is a rich document, and rich documents often include meaningful inline images that should be stored with the document.
Again, that YOU don't like this doesn't mean it's not useful or widely used by other people.
But where is this kind of email happening besides the spam box? The way you argue this should be common and hit me in the face every day no matter my resistance. What I see is that less and less fluff is added to emails. A lot of work emails don't even contain a footer anymore, less and less people actually use greeting formulas, in some regards the whole communication moved from emails to other media like social media (even at work, where it is just a inhouse FB clone instead of the original).
Can you name a few examples of such rich media emails you recently received or sent and to/from whom (categorywise, e.g. family member, colleague, customer, department type)?
Obviously, people use email in different ways. This thread seems to have attracted a large number of people who exist in a text-only email world, but nearly every email I send or receive includes at least some rich formatting, and it's very common for us to include inline images of screenshots or other graphics as part of these emails.
And we're not web designers. We make project management software.
So: for me, mostly work email, though I certainly get no small number of personal mails with photos attached.
Again, that YOUR experience with email doesn't include rich text or inline images outside your spam folder doesn't mean those features are valuable and useful to other people.
I submit your understanding of how email works for most people in 2017 is outdated.
Email with inline images is common, useful, and not going anywhere.