The biggest problem, IMO, is the idea that grammatical redundancy is erroneous, or even a bad thing at all. A bit of redundancy can make meaning clearer and avoid misunderstandings. Yes, “a pizza” and “a pizza pie” mean the same thing, but the second one might be a little clearer to someone who misses the article.
Who in the hell doesn’t know what a ‘pizza’ is? My only problem with the phrase is that it makes anyone that says it sound like they just stepped out of a 1950’s sitcom. Pies are pecan, cherry or even lemon meringue if you want to go crazy. There are even meat pies but pizza is not among them. Pizza shouldn’t be called a pie just because it isn’t one. Real pizza (not Chicago style) has neither a filling nor pastry base so it isn’t a pie.
Pony-boy
I think you’re already halfway there in more-or-less dismissing such people, and expressing your own opinions and soliciting the opinions of others on these interesting usage issues.
But you still seem to retain some sense of deference to such people in calling them “academic purists”. They don’t warrant that name, and they don’t deserve deference. They are certainly not academic, since they invariably lack much understanding of the nature of language - no academic linguist treats speakers this way or devotes energy to condemning common usage as objectively wrong. And since such people tend to express their ideas from a position of ignorance, any “purity” that they might aspire to is usually utterly misguided. Rather than calling them “academic purists”, you might feel more confidence to defy their arbitrary and invented notions and to embrace the language with your own style and eloquence if you referred to them more dismissively as “rigid prescriptivists”. And don’t be intimidated by the fact that historically their ranks have included some great writers such as Jonathan Swift and George Orwell; and more recently pundits such as Strunk & White and William Safire, and most of the staff of the New Yorker.
Given your curiosity about some interesting aspects of language, I’d recommend Stephen Pinker’s The Language Instinct. Or check out the Language Log blog, which frequently discusses such issues, with contributions (and many comments) from actual linguists. It has been around for a long time, so it’s often worthwhile searching topics in past posts.
As for a couple of the specific questions that you raise:
Redundancy.
I think the correct response to such a criticism of pizza pie is to question the premise that avoiding redundancy is something we should aspire to in language. Is it really anyone’s objective to reduce speech to the minimum number of syllables that adequately express a concept? If so, surely Shakespeare was just getting a bit repetitive after around the third sonnet. If Dean Martin coined pizza pie, it was for alliteration, for rhyme, perhaps just for fun. Rather than redundancy, the relevant question is whether we subjectively feel that it expresses what we want to say about the food accurately, eloquently and with style.
More perfect.
Language is not a computer program, and perfect unassailable “logic” it’s not an ideal any sensible speaker aspires to.
(Although the relationship between natural language and unambiguous logical syntax is extremely important for AI for, and see here for example: Lojban - Wikipedia )
With “more perfect” the only relevant question is, again, whether it expresses what we want to say about an idea accurately, eloquently and with style. My opinion is that it succeeds on all counts, expressing rather beautifully the idea of approaching more closely to an ideal. If your English composition teacher claimed that the idea conveyed by the expression was unclear, the teacher was surely being disingenuous in order to try to validate an unjustified criticism.
The most entertaining example of what we do with adopted foreign words and phrases is “The Los Angeles Angels”. (Especially since they are now no longer in Los Angeles, but Anaheim.)
For what it’s worth, I tend to think that hoi polloi is fully adopted, so personally I’d say “the hoi polloi”.
This is the kind of thing where objective analysis of usage in a corpus can be helpful, both to see if our subjective impressions are widely shared, and to look at changes over time. Google ngram viewer is a great tool:
You’ll see that a large proportion of instances of “hoi polloi” prepend “the”. It’s interesting how much the expression increased in frequency from 1900-1945. The politics of that period?
Personally, I’m a fan of “the La Brea Tar Pits” in the redundancy category, as I’m sure I’ve brought up a half dozen times here on the Dope.
Google “Pizza rustica.” “Pizza” is a pretty expansive term.
I prefer “piazza.” Just rolls off the tongue.
I could less [sic] whether you say pizza or pizza pie. I don’t have my dictionary available, but I am not even certain that “pizza” is Italian for pie.
But I did want to comment on J vs. I and so on. I was once searching in a library in Germany for a book by someone named Isbell. There were no books under I and I found it under J: Jsbell. I am sure that once upon a time in English, J was just the initial form of I. Similarly for U and V. Ever seen an inscription for JVLJVS CAESAR? I assume from the name that W was formed when U and V were the same. I think Y also originated as a variant on U/V.
A little hard to chew, though – can make teeth just roll off the tongue.
Since you bring that up…
“Hoi” means “high,” and “polloi” means “people,” so the “hoi polloi” are the high people, the social elites, the wealthy.
Except, that’s totally not true. But I keep thinking that’s what it ought to mean, so the phrase keeps confusing me.
Bulgari still uses that in their wordmark; the label reads BVLGARI.
Do you have a reference for this? I have no Greek at all, but Wikipedia and a few other quickly googled source seem to agree with the OP that “hoi” is the definite article, and that the literal translation is “the many” or “the majority”.
ETA - sorry, forget it, I just took in what you meant in your last sentence!
I take “more perfect” as political-speak. Saying, “make it perfect” opens you up to your opponent saying, “you mean there’s something wrong with it now? Where’s your patriotism?!” Saying, “more perfect” is a way of saying, “it’s perfect now, even though I want to change it, and it will be perfect after I change it, too”.
It’s not an irrational phrase describing a sensible concept. It is a rational phrase describing a nonsensical concept.
The technical term is “juvenile centaur.”
Something just to reinforce the redundancy removes ambiguity concept- the original “hamburger” was a “hamburger steak”, not a sandwich like you mention. So “hamburger sandwich” wouldn’t actually be redundant in this situation.
Personally, while I don’t really find it redundant or particularly edifying, the term “pizza pie” strikes me as really quaint- like one of those things someone who said “23 skidoo!” and wore onions on their belt might say.
Hey, good catch!
Although didn’t J.R.R. use an accent mark on the u? That would disambiguate… if anyone paid any attention to things like that in English, one of the few languages that doesn’t use any sprinkles on our alphabet, so they just look like random sprinkles, decorations, instead of bearing any meaning…
To mine it makes the speaker sound like Ned Flanders or some other completely *unhip *character.
But it gives a whole new meaning to ‘chewing up the scenery.’ 
Yup, I think that captures it for me too! Either Dean Martin or pizza-pie-diddly.