Remathilis
Legend
But, you've also kinda missed the point. If 4e elves are making elves into not elves, why are 5e elves suddenly all elf again? The only difference between 4e Eladrin and 5e High Elves is a proper noun. That's it.
Which pretty much serves as very good evidence for my point. Canon only matters when it can be used to tell other people they are playing wrong. 4e Eladrin make "elves into not elves" because they rewrite how elves were portrayed, apparently. But, 5e High Elves are pretty much word for word exactly the same as Eladrin, save the proper noun, and suddenly nothing is being rewritten, this is how elves have always been.
Canon is only important when it can bludgeon people.
Canon establishes a baseline set of assumptions. A lingua franca.
If we're playing D&D and I say, "You enter a room and there is a gnome and troll, roll for initiative" you will naturally default to the PHB gnome and MM troll. Now, if you decide to shoot the troll with a fire bolt spell (ya know, regeneration) and then I tell you "sorry, but in my world, gnomes are 20 foot tall monsters of pure evil and trolls are two-foot tall fey with gems in their stomachs, you just murdered a LG captive." You'd rightfully be pissed. I mucked up the canon. More importantly, I didn't inform you of that before you encountered that situation (something that the character would be aware of, if he lives in that world). Now sometimes its useful to turn PC assumptions on their heads, but to me players should be allowed to "learn" the game as much as anyone.
Now, lets bring this back to how 4e mucked up canon. As part of their "grand revision" of 4e, they basically chucked any mythos they though didn't make the game "cool". Cool be the subjective term Collin's et all used whenever the established idea didn't meet their idea of a darker, edgier D&D. So through the cows of D&D, the slaughter did reign. Angels are too good-two shoes; lets make them dark and edgy beings who can be fought. Metallic dragons are Good? Lets make them unaligned and antagonistic. So many monsters got radical redesigns, it often times felt insulting. Check out this post in the firbolg threat for a great example; they went from peaceful minor giants to bloodthirsty members of the Wild Hunt. That's cool if you don't want your game to have any established connection with the lore before it, but when you bill it as "ze game iz ze same" and then you force monsters into whole new roles, your giving anyone who used those monsters before a middle finger.
When I converted from 2e to 3e, I could absorb the core assumption changes fairly well. Dwarves could be wizards, but rarely were due to tradition. Some previous PCs who were nominally described as wizards became sorcerers if it fit better, ditto fighter and barbarian. I had half-orcs in my game since the Humanoid's Handbook, and tieflings since the Planeswalker's Handbook. The changes were minimal. But 4e forced massive areas of re-write. All tieflings looked alike. Elven PCs who previously had no magical ability could suddenly teleport every 5 minutes. Blue dragons hung out in the coastal areas, not the desert. The list went on. In order to convert my world from 3e's assumptions to 4e's I had to have a spell-plague like cataclysm and a massive amount of hand-waving to align with the new canon. It changed my world so radically, I ended up scrapping it and using PF with 3e assumptions until 5e, where I could pretty much use my world as I did in 3e with a few minor changes (basically, accounting for dragonborn).
In 4e, they tossed out the old Lingua franca and made us use a new one. They swapped our gnomes and trolls. They broke iron-bound rules (like Eberron's race-based dragonmarks) just to give PCs another "power-up" toy. They liberally stole the unique ideas from other setting (warforged, vistani, draconians) and threw them into POLsilvania just because they could. Most important, they ignored the tradition set by Gygax, Anderson, Cook, Marsh, and countless others because it wasn't "cool" enough.
And yeah, Eladrin were part of it. A huge part. My namesake character could now teleport. Through iron bars. Every 5 minutes. You know how that ability would have changed his history? Far more than casting Fire Bolt or True Strike could.
Canon is only a bludgeon when people insist tradition, and lingua franca, doesn't matter. Play the game you want, but don't get mad when you end up murdering LG treasure trolls...