That title is unique for one reason. So few have it. Not Invincible few, nor Deathcharger few. Way, way fewer.
Give it to everyone and it’s just another title (not even a very good one) like Dragonslayer (a cooler title but anyone can have it).
Generally I agree with you that content shouldn’t be removed but this one specific title and mount are sacred in the game’s history.
Removing the MOP cloak and the WoD ring were silly, mostly as they removed the quests that went with them which had significant lore details and also it gated access to the Ordos area on the Timeless Isle.
But they’ve stopped removing such questlines since then, I think they realised how silly it was and how it damaged the game especially for new players.
The Mage Tower weapon skins was another mistake and I think they’ve learnt from this too, they didn’t remove the Island Expeditions and the mogs from that nor Torghast and its mogs.
They do have season rewards that get removed but these are generally recoloured mounts so no big loss.
The Scarab Lord rewards is a strange hill to fight your battle on. The Mage Tower mogs would garner you more sympathy from forum members.
Although I think there’s a good chance most of them will get some recoloured versions put on the Trading Post at some point.