As far as I am aware, except for 4e when "Elves" were replaced by Eladrin, Elves have always been at least a little bit magic. If you look at ADnD they advance furthest in Magic user and of course can multiclass Magic user with Fighter and Thief (and frankly why would you not). Basic has all Elves being Fighter/Magic Users and even 3e has Elves favoured class as being Wizard.
So unless you started in 4e with no idea of the Elven history in DnD and pre-DnD source material, why it blow anyones mind to find out that in 5e all High Elves can cast a cantrip? You may as well get upset that an underground mining race like Dwarves use Axes.
But here's the part that confuses me. What is so different about 4e elves then? Why are 4e elves a complete rewrite of elves in D&D, but, 5e elves are just business as usual?
4e changes the name, gives them an at-will spell, and makes them fey.
5e leaves the name, gives them an at-will spell, and makes them fey.
But, 4e is the massive rewrite of the race? Bwuh?
And, since we're being exactingly specific here, actually, you are mistaken about AD&D elves. They advance furthest at thieves, as all races (IIRC) were unlimited in levels of thief. Actually did a little fact checking. I apologize, I made a mistake. Half orcs were limited to 8th level thieves (with the possibility of higher levels with higher stats). Note, apparently as well, elves make great assassins, since their third highest limit at only one level less, was assassin. So, elves were unlimited as thieves, limited to 11th as magic users (if they had an 18 Int) and 10th as assassins.
So, basically, the only real difference between a 4e eladrin and a 5e elf is the name.
Now, @Imabanana, this is what I'm holding up as proof of people only claiming the importance of canon when it's convenient.
I mean, look, if lore and canon was as important as you say, 3e should have been crushed. It radically changed EVERY setting. Two changes in 3e rewrite every setting - every race can be every class with no restrictions, and the magic item economy. Those two changes have enormous implications on every single setting. But, people liked the change. They though (by and large) that this was a pretty good idea.
So, what did they do? They retconned every single setting to allow for these changes. You now have halfling clerics running around in Forgotten Realms. You have wildmage gnomes in Dragonlance. So on and so forth. And most people, by and large, have no problems with any of this despite the fact that they've now retconned and rewritten EVERY SINGLE SETTING. And that's okay. Because we
like that change. And players in 3e expected to be able to buy magic items. The write-ups for towns come with GP limits and the advice in the DMG to allow the players to buy anything they like under that limit. Poof, magic item economy, which didn't exist in the game previously is now slotted into the settings. One day I can't buy a +1 sword anywhere in Waterdeep and next day, poof, magic item stores all over the place.
But, apparently, canon isn't an issue? Because... reasons?
Canon only matters when people want to tell other people how to play the game.