It's more than that. The initial blurbs don't contain enough information, but with context you can make solid guesses about what should go in.
So it's
* small explanation
* initial proposal of what you probably want
* fixes and approval
Not really any different than asking a person to do it for you.
You don't tell your car/mapping software the exact route you want, you tell it where you want to go and then review the proposed plan, and that's with a very restricted setup (exact destination, limited routes).
Edit
More importantly, short messages that convey everything you want with the right tone are hard. Taking my mashed thoughts and converting them to easier to understand prose is a benefit even if it's longer.
Just like a larger function can be better than a code-golfed one. It's longer but it doesn't take longer to read.