Board Thread:Lore Discussion/@comment-26248987-20160107050227/@comment-1600847-20160913143849

In response to OP, because players would be mad if they couldn't buy the house based on their race. The same reason, in my opinion, why Bethesda made it possible for non-human races to join the Stormcloaks.

If you're looking for a non-"Bethesda not wanting to piss of players" reason, likely because:

A) By the time you can buy it, you've pretty much won the war for Ulfric, so you're on his good side unlike the other Argonians at the docks.

B) You can afford it. Money can make people ignore a lot of prejudices.