After all, ESO lore is approved as canon before it can be in the game by Bethesda, and it has the Dunmer, Nords, and Argonians work together.

The same reason the Dunmer still hate Argonians regardless?

Argonians hate Dunmer, Dunmer just had them as salves

I dislike Nords same reason I hate Orcs, their cultures are to primitive.

Give me a Imperial or Altmer any day of the week..

The oddest image just entered my head of Dunmer having Argonians applied to their burns.

Because things change in a thousand years and the whole ebonheart pact is laughable, Dres, Indoril and Hlaalu giving up their slaves, second era Dunmer and argonians working together, the Nords and Dunmer being allies only works because they fought alongside each other during the Kamal Invasion which didn't become lore until TES:O.

"Dunmer hate everyone equally" as a great quote goes.

I think that is really only Dres, and even than they are fairly welcoming to potential clients. The thing is the Dunmer don't care if the outsider is just visiting or if they earned their place in the community the Dunmer in Morrowind as a whole are xenophobic, not really the same as racist, because they've spent generations alone n their own with only contact being some outside traders, a tribe in argonia that caught slaves for them and one in elsewyr too and the Sload and even than it's mostly Dres and HLaalu, Redoran's interaction with outsiders is always hostility because of the nords and Indoril and Telvanni are so far into Morrowind that they have become xenophobic by not having seen outlanders in ages.