Except the Altmer philosophy is and always has been one of racial superiority. Overplayed or not, their still racial supremacists and even look down upon their fellow mer and throw them in with scum like men.
Is there any race in Tamriel that doesn't look down on every other one? All the Altmer add to the mix are their long ancestry and the golden skin. And their recent success, I guess.
Issue is their idea of paradise means the death of everyone else and opportunity of obtaining something greater than their original state.
The death of everyone else includes them turning back into divine spirits as well (and reincarnating into Mer in the meantime). It's all or nothing - either everyone transcends or nobody does.