I've started using an equivalent pattern and my implementation has generally been a success, so I'll share:

My email body has everything the "optimal" reader (i.e., someone who is already familiar with the topic item) needs to |action_verb| regarding what I've written.

Then I "conclude" with my usual sign-off (e.g., Cheers, [CRLF] "/Aceyman").

BELOW that—but above my default signature/contact info block—I place all the deeper-dive / expository / rationalization narrative which provides that level of detail for anyone who needs more than my main body provides.

I've been using this pattern for about a year or so with good results.

/Acey

At the start of the supplementary section—and depending on the topic & audience—I'll sometimes use the 'section title' Extra-credit reading, because everyone loves a chance for some extra-credit, right? That's my little psych ploy to entice readers to take a look at the nominally 'optional' expository stuff.

I have started to question the value of sign-off text. It seems that is just wastes screen space. The only time it would be useful is when you are emailing someone who might not know who you are. What value do you see in it?

It's a signal that you're in the "in" group of the cultural norms, like shaking hands or the superfluous "Hi" in text chats. The value is social signaling and emotional, not informational.

Good on you for thinking about the user experience of the person receiving the communication. It's a skill to know how to do this well. It requires practice and effort that many people don't bother with – because of a lack empathy, they're too busy, or they realize the recipient(s) won't recognize (or even read) the results.

Edit: In my experience, a lot of people can't even bother to think of an appropriate subject line that summarizes the content effectively. "URGENT: please read" is the worst offender.

Communication is a weak point in the entire software industry. It permeates everything from emails to variable names. I wonder if it's the same in other industries.