HTTP is not elegant. I can disprove its elegance with one word: referer [sic]
Keep in mind that Hypertext as it was originally envisioned by Ted Nelson had nothing but two way links, doing one-way links broke with the view of the day in a pretty drastic manner (and actually made the whole thing possible), so I think some leeway here is allowed.
Right ;)
I worked a bit for a small newspaper in Amsterdam in the 1980's, called 'the paper about Holland'. It was written by two UK journalists, Abi Daruvalla and Mark Fuller.
We were pretty good at proofreading because spell checkers were non-existent at the time, we barely had a word processor. It would probably surprise you that as a non-native English speaker I would catch typos (not grammar errors) much quicker than the rest of the (native speakers/writers) crew. We figured it was because they didn't actually read the words where I had to. They'd mentally fill in the word that should have been there which allowed them to proofread a piece with three individuals and I'd still catch the mistakes in the spelling.
In spite of that we managed to ship two issues labeled September in one year, and that's with everybody being so focused on the spelling that nobody bothered to check the dates.
I think you're reading way too much in a single letter spelling error (which I spotted the first time I saw the word), the common excuse is that the spell checker used by the person that wrote that part did not include a spelling for 'referrer' (and if it had it would have probably ignored it with the leading capital anyway...).
I've seen some pretty elegant code with terrible spelling errors in the variable names, it's certainly not great to have a spelling error in a text protocol. But I would not use that single letter mistake as a yardstick by which to measure the entire protocol, that seems all too easy a way to discard something that has stood the test of time very well.
Imaginary meat. Sure, you can talk about the implications of the actual header, but you must first acknowledge that this has nothing whatsoever to do with the context of 'elegance'.
HTTP's popularity outside of the web is mainly cause it's easy to use as a simple wrapper around TCP with read and read/write semantics. Nearly all the rest of HTTP is unneeded fluff (proof: browsers didn't even do other methods besides GET/POST and applications were just fine).