Except using the same name does confuse things (I'm not sure why you'd claim otherwise).
Who is confused?
You don't seem to be. Nor does [MENTION=11697]Shemeska[/MENTION]. I am not (and I have a copy of Jeff Grubb's MotP, which I bought and where I first read about archons in 1987).
James Ward's DDG repurposed the concept of "Titan" to describe the mostly evil proto-gods of Greek Myth (as opposed to the mostly noble and generous quasi-divine giants of the 1st ed D&D MM). Somewhere - I think in Jeff Grubb's MotP - there was a brief explanation of how the word "Titan" did double duty. I don't think many people suffered from serious confusion.
It means that if you use pre-4e archons you've got to rename them... or go the extra mile to explain, yes, these are archons but they're not the same archons. In fact, they're nothing like those other archons who happen to share the same name. Don't worry. It makes sense.
To whom are you making this explanation? Players who have read the 4e MM (or are using Arcane Power to build a summoning wizard), and hence have learned what 4e archons are, but who aren't familiar with the prior material, but with whom you want to use the prior material? How many players are in that category? How many times did you have this problem in the course of your 4e campaigns?
Until your post I hadn't even turned my mind to this confusion issue, but now that I have I don't see that confusion is going to be very rife.
Except that's a major simplification of 4e eladrin vs. pre-4e eladrin. One's a celestial race with intrinsic dies to chaotic good deities. One's high elves with some extra magic. And that's not an exaggeration - in the Forgotten Realms 4e eladrin are moon elves and sun elves... and celestial eladrin (who were apparently the same race all along, but no one knew).
I don't know very much about the ins-and-outs of FR lore either pre- or post-4e.
But personally, I don't see a major difference between "celestial race" (= magical race with a few bells and whistles) of pseudo-elves with intrinsic ties to CG deities, and "magical race" with intrinsic ties to the deities of Arvandor (which was, in Planescape-oriented presentations, a CG plane).
I'm not comfortable with the word "disrespect" in this context, but it certainly is more than just a representation of the same material. There were some major rewrites of the lore going on and it wasn't just Planescape fans who were disgruntled by it.
It isn't
certainly more than just a representation of the same material. What is changing the nature of a mercurial, magical elven race from "celestial" to "fey"
but a new presentation of earlier material? It is not making up something new from whole cloth.
There's room for discussion about how faithful West Side Story is to Romeo and Juliet, and whether the change in the ending is better, worse or just different - but to say that because the setting is moved from Italy to NYC it simply can't count as a reworking of the older material would be silly. Being set in Italy, rather than NYC, just isn't so integral to Romeo and Juliet that you can't keep the gist yet lose that feature. My view is that identifying the essence of Eladrin with game-mechanical concepts like "celestial" rather than "fey", as opposed to story/thematic concepts like "mercurial, otherworldly elven beings" which are preserved in 4e, is precisely the sort of thing I talked about upthread: a focus on minor details rather than thematic resonance and story function.
fans of published campaign settings don't like to see the boat rocked very much
I'm sure that's true. But that doesn't rebut my point. From my point of view it might rather be a confirmation of it.
Furthermore, D&D isn't a "published campaign setting": it is not a work of fiction. The story elements published in the core D&D books - monsters, PC backgrounds and classes, etc - are intended for use by D&D players to create their own works of fiction. (Of course, some players aren't as interested in the story elements as the more nitty-gritty challenge elements, which is fine too.) At most, they carry hints of theme or content for players to pick up and adapt to their own purposes. (See eg the interesting current thread "Evil enough", about tiefling warlock backstory.) In presenting this sort of stuff, it's fine for designers to be inspired by what came before but I at least want them to produce the best that they can. Not simply to republish a recap of what came before with a few extra additions, like some never-ending chain novel. People who love the old versions still have their old books to read.