Basically the Blood Elves use of mana tap made them hunger more and more according the chronicles.
The Sunwell now just gives them an infinite fix with no side effects. They aren’t actually “Cured”.
High Elves on the other hand went the path of moderation and thus need it far less then Blood Elves.
Even in Ions famous quote that people said means “No” he says their relation to the Sunwell is different.
Also, gold eyes lorewise is more for light users but they did not want to restrict it for players.
As the video says, Sunwell infused Eyes = Gold.
Arcane can’t purge Fel. Light can because it’s a greater power in the universe only equal to Void.