Because they are just general features for the respective races.
It’s not up to you or me to decide what people’s characters should look like.
Night Elf Mages will also have purple leaves which can be seen as “Highborne features” as they are the most nature-based Highborne around as they spent in Feralas, years after the Horde exiled them from Dire Maul.
If little-johnny decides he wants to make his Dwarf Warlock look like a Wildhammer Dwarf - more power to him.
Two did and they were both killed.
And we have to be realistic here - Blizzard seems intent on only writing them in as a last resort. They could have easily included them in Azsuna, but they didn’t - they used undead Highborne and Kirin Tor Night Elf Mages.
Not quite correct.
They just aren’t too interested in the Shen’dralar and I can see why. Where do you fit them into a story that has Humans, Blood Elves, Nightborne, Void Elves and Draenei Magi, who’ve had far more exposure to the lore?
Literally, Shen’dralar are only used to either stand around or to open portals, but we’ve seen this countless times by the Humans.
It’s still the same means, via fel/demonic use. Blood Elves used both Demons and Fel Crystal and the Shen’dralar just had a single demon.
Also, again - this feature is for a very small sector of night elf society. These people have been killed thrice over. We have to really see what is acceptable in night elf society.
A fel-eyed night elf would either be exiled or killed - the latter, most likely. The Shen’dralar, in their exile, spent their time weening off fel magic.
But why does this need to be shared? I mean, can’t you think of other features instead of wanting things from the Blood Elves?